agent: lumotia-rebrand — localStorage keys + event channels migration

Phase 7 of the rebrand cascade. Persisted UI state + inter-window event
channels migrated from magnotia to lumotia naming, with one-shot
localStorage key migration so dogfooded UI state survives the rename.

src/lib/utils/localStorageMigration.ts (new):
- migrateLocalStorageKey(old, new): idempotent + crash-safe shim.
  - If new key exists, removes old (lumotia value is authoritative).
  - If only old exists, copies value to new key, removes old.
  - If neither, no-op.
- migrateLocalStorageKeys(pairs): batch wrapper.

src/lib/stores/page.svelte.ts:
- 4 key constants renamed to lumotia_settings / lumotia_profiles /
  lumotia_task_lists / lumotia_templates.
- BroadcastChannel name renamed to lumotia_task_lists.
- migrateLocalStorageKeys() called at module load before any read.

src/lib/stores/focusTimer.svelte.ts:
- STORAGE_KEY renamed to lumotia.focusTimer.v1.
- migrateLocalStorageKey() called at module load.

Event channels (magnotia: -> lumotia:) renamed across frontend + Rust:
- magnotia:toggle-recording (src/routes/+layout.svelte)
- magnotia:hotkey-pressed / -released (src-tauri/src/commands/hotkey.rs +
  consumers)
- magnotia:open-wind-down (src-tauri/src/tray.rs + consumer)
- magnotia:llm-download-progress (src-tauri/src/commands/llm.rs)
- magnotia:preferences-changed (src/lib/stores/preferences.svelte.ts +
  consumers)
- magnotia:start-timer (nudgeBus + dispatch sites)
- magnotia:focus-timer-{complete,cancelled} (focusTimer + nudgeBus)
- magnotia:microstep-generated (nudgeBus + dispatch sites)
- magnotia:step-completed (nudgeBus + dispatch sites)
- magnotia:task-{completed,uncompleted,deleted} (page.svelte.ts +
  nudgeBus + consumers)

Storage-event filters in src/routes/{float,viewer,preview}/+layout@.svelte
updated to filter on lumotia_settings.

User-facing toast strings still say "Magnotia" — deferred to Phase 8
(frontend strings).

npm run check: 0 errors / 0 warnings (3958 files).
cargo test --workspace: 339 pass / 0 fail.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/stores/implementationIntentions.svelte.ts

@@ -13,7 +13,7 @@ import { page, settings, tasks } from "$lib/stores/page.svelte.js";
 import { toasts } from "$lib/stores/toasts.svelte.js";
 
 const TIME_RULE_POLL_MS = 30_000;
-const RULES_CHANGED_EVENT = "magnotia:implementation-rules-changed";
+const RULES_CHANGED_EVENT = "lumotia:implementation-rules-changed";
 
 export const implementationRules = $state<ImplementationRule[]>([]);
 
@@ -157,7 +157,7 @@ async function executeAction(action: ImplementationRuleAction): Promise<void> {
     return;
   }
   if (action.kind === "start_timer") {
-    window.dispatchEvent(new CustomEvent("magnotia:start-timer", {
+    window.dispatchEvent(new CustomEvent("lumotia:start-timer", {
       detail: {
         taskId: action.taskId ?? null,
         seconds: 300,
@@ -239,8 +239,8 @@ export function startImplementationIntentions(): void {
   void loadImplementationRules(true)
     .then(() => checkTimeRules())
     .catch(() => {});
-  window.addEventListener("magnotia:task-completed", onTaskCompleted);
-  window.addEventListener("magnotia:morning-triage-finished", onMorningTriageFinished);
+  window.addEventListener("lumotia:task-completed", onTaskCompleted);
+  window.addEventListener("lumotia:morning-triage-finished", onMorningTriageFinished);
   window.addEventListener(RULES_CHANGED_EVENT, onRulesChanged);
   timePollHandle = setInterval(() => {
     void checkTimeRules().catch(() => {});
@@ -250,8 +250,8 @@ export function startImplementationIntentions(): void {
 export function stopImplementationIntentions(): void {
   if (!started) return;
   started = false;
-  window.removeEventListener("magnotia:task-completed", onTaskCompleted);
-  window.removeEventListener("magnotia:morning-triage-finished", onMorningTriageFinished);
+  window.removeEventListener("lumotia:task-completed", onTaskCompleted);
+  window.removeEventListener("lumotia:morning-triage-finished", onMorningTriageFinished);
   window.removeEventListener(RULES_CHANGED_EVENT, onRulesChanged);
   if (timePollHandle !== null) {
     clearInterval(timePollHandle);