feat(energy): Phase 3 — match-my-energy task sort + tri-state tag column

Closes Phase 3 of the 2026-04-23 feature-complete roadmap. Incorporates
the Codex plan-review fixes from this session: profile-free index, tri-
state update command, and de-prioritise-not-hide semantics.

Storage (kon-storage):
- Migration v11 adds `energy TEXT` to `tasks` with a CHECK constraint on
  `high | medium | brain_dead | NULL`. Index `(energy, created_at DESC)`
  — deliberately not per-profile because the tasks table carries no
  profile_id column yet (tracked as a separate gap in HANDOVER).
- `TaskRow.energy: Option<String>` plus `task_row_from` read.
- `insert_task` signature grows by one optional arg (`energy`). Allowed
  `too_many_arguments` with a rationale comment — the positional shape
  matches the column order and flipping to a params struct would have
  rippled through every caller for cosmetic benefit only.
- New `set_task_energy(pool, id, Option<&str>) -> TaskRow`. Lives as its
  own function because `update_task` uses COALESCE to let `None` mean
  "preserve" — which would make clearing the tag impossible.
- Two new tests: round-trip including explicit NULL clear, and CHECK
  constraint rejection of unknown values.
- Tests updated for the v10 → v11 version bump.

Tauri (src-tauri):
- `TaskDto.energy`. `CreateTaskRequest.energy` (optional). Inline
  validation against the allowed set before hitting the DB, so frontend
  bugs surface as friendly errors instead of CHECK-constraint failures.
- New `set_task_energy_cmd` command mirroring the storage tri-state API.

Frontend (svelte):
- `EnergyLevel` type added to `types/app.ts`. `TaskDto`, `TaskEntry`, and
  `TaskDraft` grow an `energy` field.
- `SettingsState.currentEnergy` (persisted) + `matchMyEnergy` (persisted
  toggle). Defaults: null + false — no surface change until user opts in.
- `setTaskEnergy(id, EnergyLevel | null)` action on the task store.
  Calls the dedicated Tauri command, updates local state, broadcasts to
  sibling windows.
- `EnergyChip.svelte` — new component. Cycles unset → High → Medium →
  Brain-Dead → unset on click. Colour tokens: accent / warning /
  text-tertiary (deliberately not danger-red for Brain-Dead — the brief
  is explicit that this state must not feel pathologised).
- Chip rendered on every task row in TasksPage and every row in
  WipTaskList. Hidden-until-hover when energy is unset so untagged rows
  stay calm; always visible once tagged because the colour is the signal.
- Tasks page header gains a "I feel" segmented control and a
  "Match my energy" toggle. When both are active, matching tasks sort
  to the top — unset tasks are treated as Medium-equivalent. Nothing is
  ever hidden; this is a de-prioritisation, not a filter.

Deferred / out of scope:
- LLM-driven surfacing (brief says "The AI surfaces...") — deterministic
  client-side sort is v1; LLM layer is a later phase.
- tasks.profile_id + per-profile energy sort — separate migration.

All green: cargo build + 251 tests + clippy -D warnings (0 warnings)
+ fmt + svelte-check (0/0) + npm run build.

src/lib/pages/TasksPage.svelte

@@ -1,14 +1,17 @@
 <script lang="ts">
   import { tick } from "svelte";
-  import type { TaskBucket, TaskList } from "$lib/types/app";
+  import type { EnergyLevel, TaskBucket, TaskEntry, TaskList } from "$lib/types/app";
   import { invoke } from "@tauri-apps/api/core";
   import {
     tasks, addTask, completeTask, uncompleteTask, deleteTask, updateTask,
+    setTaskEnergy,
     taskLists, addTaskList, renameTaskList, deleteTaskList,
+    settings, saveSettings,
   } from "$lib/stores/page.svelte.js";
   import WipTaskList from '$lib/components/WipTaskList.svelte';
   import EmptyState from '$lib/components/EmptyState.svelte';
-  import { SquareCheck, Search, ExternalLink, ChevronLeft, ArrowUpDown, Plus, X, ChevronRight } from 'lucide-svelte';
+  import EnergyChip from '$lib/components/EnergyChip.svelte';
+  import { SquareCheck, Search, ExternalLink, ChevronLeft, ArrowUpDown, Plus, X, ChevronRight, Zap } from 'lucide-svelte';
   import Card from "$lib/components/Card.svelte";
   import { formatTimestamp } from "$lib/utils/time.js";
   import { BUCKET_COLORS, EFFORT_LABELS, EFFORT_ORDER } from "$lib/utils/constants.js";
@@ -47,6 +50,17 @@
     return EFFORT_LABELS[effort as keyof typeof EFFORT_LABELS] || effort;
   }
 
+  // Phase 3 energy sort: when the user has opted in and declared a
+  // current energy, tasks matching that energy sort to the top. Tasks
+  // with no energy tag are treated as Medium-equivalent, per the brief's
+  // framing that unset is the normal case. Nothing is ever hidden —
+  // "reserves" in the spec means de-prioritise, not filter.
+  function energyMatchRank(task: TaskEntry, currentEnergy: EnergyLevel | null): number {
+    if (!currentEnergy) return 0;
+    const effective = task.energy ?? "medium";
+    return effective === currentEnergy ? 0 : 1;
+  }
+
   let filteredTasks = $derived.by(() => {
     let list = tasks.filter((t) => !t.done);
     if (activeBucket !== "all") {
@@ -68,9 +82,34 @@
     } else if (sortMode === "deep-first") {
       list.sort((a, b) => effortRank(b.effort) - effortRank(a.effort));
     }
+    // Match-my-energy sort runs last (stable) so it reorders the result
+    // of the effort-based sort rather than replacing it.
+    if (settings.matchMyEnergy && settings.currentEnergy) {
+      const energy = settings.currentEnergy;
+      list.sort((a, b) => energyMatchRank(a, energy) - energyMatchRank(b, energy));
+    }
     return list;
   });
 
+  function cycleCurrentEnergy(next: EnergyLevel | null) {
+    settings.currentEnergy = next;
+    saveSettings();
+  }
+
+  function toggleMatchMyEnergy() {
+    settings.matchMyEnergy = !settings.matchMyEnergy;
+    saveSettings();
+  }
+
+  function energyLabel(level: EnergyLevel | null): string {
+    switch (level) {
+      case "high": return "High";
+      case "medium": return "Medium";
+      case "brain_dead": return "Brain-Dead";
+      default: return "Not set";
+    }
+  }
+
   let completedTasks = $derived.by(() => {
     let list = tasks.filter((t) => t.done);
     if (activeBucket !== "all") {
@@ -199,6 +238,49 @@
       <p class="text-[11px] text-text-tertiary mt-1">Add tasks manually. Automatic extraction from your transcripts is coming.</p>
     </div>
     <div class="flex-1"></div>
+
+    <!-- Phase 3 match-my-energy control. Three-state energy selector +
+         toggle for the sort. Sits in the header so it is always visible
+         from any bucket / list context. -->
+    <div class="flex items-center gap-2 mr-2">
+      <span class="text-[10px] text-text-tertiary hidden sm:inline" aria-hidden="true">I feel</span>
+      <div class="flex items-center gap-0.5 bg-bg-input border border-border-subtle rounded-lg p-0.5"
+        role="radiogroup"
+        aria-label="My current energy">
+        {#each [
+          { value: null, label: '—' },
+          { value: 'high' as EnergyLevel, label: 'High' },
+          { value: 'medium' as EnergyLevel, label: 'Med' },
+          { value: 'brain_dead' as EnergyLevel, label: 'Low' },
+        ] as opt}
+          <button
+            class="text-[10px] px-2 py-0.5 rounded-md
+              {settings.currentEnergy === opt.value
+                ? 'bg-accent/15 text-accent'
+                : 'text-text-tertiary hover:text-text-secondary'}"
+            role="radio"
+            aria-checked={settings.currentEnergy === opt.value}
+            aria-label={opt.value ? `Set current energy to ${energyLabel(opt.value)}` : 'Clear current energy'}
+            onclick={() => cycleCurrentEnergy(opt.value)}
+          >{opt.label}</button>
+        {/each}
+      </div>
+      <button
+        class="flex items-center gap-1 btn-md rounded-lg text-[10px]
+          {settings.matchMyEnergy
+            ? 'bg-accent/15 text-accent border border-accent/30'
+            : 'text-text-tertiary hover:bg-hover hover:text-text border border-transparent'}"
+        style="transition-duration: var(--duration-ui)"
+        onclick={toggleMatchMyEnergy}
+        aria-pressed={settings.matchMyEnergy}
+        aria-label={settings.matchMyEnergy ? 'Match my energy is on — click to turn off' : 'Match my energy is off — click to turn on'}
+        title="Sort matching tasks to the top (unset counts as Medium)"
+      >
+        <Zap size={12} aria-hidden="true" />
+        Match my energy
+      </button>
+    </div>
+
     <button
       class="flex items-center gap-1.5 btn-md rounded-lg text-text-secondary hover:bg-hover hover:text-text"
       style="transition-duration: var(--duration-ui)"
@@ -451,6 +533,13 @@
                       onclick={() => setEffort(task.id, e)}
                     >{effortLabel(e)}</button>
                   {/each}
+                  <span class="text-border-subtle">&middot;</span>
+                  <!-- Energy chip (Phase 3) -->
+                  <EnergyChip
+                    energy={task.energy}
+                    onSelect={(next) => setTaskEnergy(task.id, next)}
+                    size="md"
+                  />
                   <!-- Timestamp -->
                   {#if task.createdAt}
                     <span class="text-[10px] text-text-tertiary ml-auto">{formatTimestamp(task.createdAt)}</span>