feat(intentions): Phase 7 — if-then rules for task / time / triage triggers

Small if-then automation layer. Rules persist in SQLite; the runner
lives on the frontend and binds to the Phase 6 event bus so the rule
pipeline reuses the same delivery primitives (timer events, TTS,
Tasks navigation).

Storage:
- Migration v12 adds implementation_rules (id, enabled, trigger_kind,
  trigger_value, actions_json, last_fired_key, created_at,
  updated_at) with enabled+trigger_kind index for the runner's hot
  path.
- CRUD helpers: insert / list / get / set-enabled / mark-fired /
  delete, plus a round-trip test.

Commands (all main-window-guarded via ensure_main_window):
- list_implementation_rules
- create_implementation_rule — validates HH:MM, checks the target
  task exists at save time for surface-task actions, caps
  speak-line at 240 chars, pins v1 timers to 5 minutes.
- set_implementation_rule_enabled
- mark_implementation_rule_fired — main-thread idempotency shim so
  the runner can atomically claim a fire.
- delete_implementation_rule

Runner (implementationIntentions.svelte.ts):
- Subscribes to kon:task-completed and kon:morning-triage-finished
  (MorningTriageModal now emits on all three exit paths — empty,
  skipped, picked — so skip counts as finishing).
- 30 s poll for time-of-day rules, plus an immediate check on startup
  so a rule whose time has already passed today catches up once.
- Idempotency via last_fired_key composed as YYYY-MM-DD@HH:MM for
  time rules; new time rules whose HH:MM has already passed today
  are pre-seeded so they don't fire retroactively on save.
- Rules are paused when Nudges "Mute for now" is on — a hard mute
  stops all rule delivery in addition to OS notifications.
- Stale-task safety: if a surface-task action's target has been
  deleted, the runner opens Tasks and warns clearly rather than
  pretending to surface something that's gone.

Editor (ImplementationRulesEditor.svelte):
- Lives in Settings under a new "If-then rules" accordion section.
- `If` picker: time of day (with time input), a task completes,
  morning triage finishes.
- `Then` composer: optional surface (inbox / today / all tasks /
  specific task), optional 5-min timer, optional speak-aloud line.
- Saved rules list with enable toggle + delete.

Rules table integration for Phase 10b rename sweep: add
implementation_rules to the kon.db → corbie.db migration shim when
that phase lands.

Gates: fmt, clippy -D warnings, cargo test 265/0, svelte-check
0/0, npm build green. Pre-existing Vite chunk warning on sounds.ts
is unrelated to Phase 7.

crates/storage/src/migrations.rs

@@ -400,6 +400,36 @@ const MIGRATIONS: &[(i64, &str, &str)] = &[
             ON tasks(energy, created_at DESC);
         "#,
     ),
+    (
+        12,
+        "implementation intentions: if-then automation rules",
+        r#"
+        -- Phase 7 of the feature-complete roadmap. Rules are local-only,
+        -- user-authored implementation intentions: "if this happens, then
+        -- do this small thing". Execution stays in the frontend event bus;
+        -- SQLite owns the durable definition and the once-per-day marker
+        -- for time-of-day rules.
+        CREATE TABLE implementation_rules (
+            id TEXT PRIMARY KEY,
+            enabled INTEGER NOT NULL DEFAULT 1
+                CHECK (enabled IN (0, 1)),
+            trigger_kind TEXT NOT NULL
+                CHECK (trigger_kind IN (
+                    'time_of_day',
+                    'task_completed',
+                    'morning_triage_finished'
+                )),
+            trigger_value TEXT NOT NULL DEFAULT '',
+            actions_json TEXT NOT NULL DEFAULT '[]',
+            last_fired_key TEXT,
+            created_at TEXT NOT NULL DEFAULT (datetime('now')),
+            updated_at TEXT NOT NULL DEFAULT (datetime('now'))
+        );
+
+        CREATE INDEX idx_implementation_rules_enabled_trigger
+            ON implementation_rules(enabled, trigger_kind);
+        "#,
+    ),
 ];
 
 /// Split SQL into individual statements, respecting BEGIN...END trigger blocks.
@@ -549,7 +579,7 @@ mod tests {
             .fetch_one(&pool)
             .await
             .unwrap();
-        assert_eq!(count, 11);
+        assert_eq!(count, 12);
 
         sqlx::query("INSERT INTO settings (key, value) VALUES ('test', 'value')")
             .execute(&pool)
@@ -568,7 +598,7 @@ mod tests {
             .fetch_one(&pool)
             .await
             .unwrap();
-        assert_eq!(count, 11);
+        assert_eq!(count, 12);
     }
 
     #[tokio::test]
@@ -596,6 +626,44 @@ mod tests {
         }
     }
 
+    #[tokio::test]
+    async fn migration_implementation_rules_adds_rule_table() {
+        let pool = fk_test_pool().await;
+        run_migrations(&pool).await.expect("migrate");
+
+        let info = sqlx::query("PRAGMA table_info(implementation_rules)")
+            .fetch_all(&pool)
+            .await
+            .unwrap();
+        let names: Vec<String> = info.iter().map(|r| r.get::<String, _>("name")).collect();
+        for col in [
+            "id",
+            "enabled",
+            "trigger_kind",
+            "trigger_value",
+            "actions_json",
+            "last_fired_key",
+            "created_at",
+            "updated_at",
+        ] {
+            assert!(
+                names.contains(&col.to_string()),
+                "implementation_rules must have {col}; got {names:?}"
+            );
+        }
+
+        let rejected = sqlx::query(
+            "INSERT INTO implementation_rules (id, trigger_kind, actions_json)
+             VALUES ('bad', 'calendar_event', '[]')",
+        )
+        .execute(&pool)
+        .await;
+        assert!(
+            rejected.is_err(),
+            "trigger_kind CHECK constraint must reject unknown triggers"
+        );
+    }
+
     #[tokio::test]
     async fn migration_transcripts_meta_adds_columns() {
         // Task 2.5 — verify starred / manual_tags / template / language /