feat(wake): probe 4 times per marked hour (:00 :15 :30 :45), coalesce same-tick fires

Marking an hour on the Claude Wake Schedule panel now schedules FOUR probes
within that hour instead of one. Rate-window edges are unforgiving — a
single probe at :15 can miss the actual reset moment by up to 14 minutes;
hitting :00 / :15 / :30 / :45 puts us within ~7 minutes of any reset that
happens during that hour.

When multiple slots come due in the same 30s scheduler tick (or recover
together at boot), they coalesce into a SINGLE upstream wake call — no
point hitting Anthropic 4× in the same window.

DB schema
- wake_schedule is now (hour, slot_minute, next_wake_at) PK (hour,
  slot_minute). Destructive migration: detect old single-row-per-hour
  schema by absence of the slot_minute column and DROP TABLE. No other
  table is touched. Per user direction: no back-compat for old rows.

API
- POST /models/wake-schedule/toggle add: { hour, timestamps: { '0': ms,
  '15': ms, '30': ms, '45': ms } } — all 4 slots required, all must be
  future Unix ms. Delete shape unchanged ({ hour }).
- GET /models/wake-schedule shape:
    schedule: { '9': { '0': ts, '15': ts, '30': ts, '45': ts }, ... }
    probeSlotMinutes: [0, 15, 30, 45]
    resetOffsetHours, lastWake, pendingRetry  (unchanged from prior commit)

Frontend
- Computes 4 timestamps client-side (next occurrence of HH:MM in local TZ)
  and sends them in one request.
- markedHours summary now says 'Probes :00 :15 :30 :45 → reset by ~Xh later'.
- Same in-flight tracking / current-hour ring / status row as before.

Tests
- wake-scheduler.test.ts unchanged (pure helpers still correct; added
  PROBE_SLOT_MINUTES + isProbeSlotMinute exports).
- routes.test.ts rewritten for the new payload shape: 12 wake-schedule
  tests covering snapshot shape, add/remove (full 4-slot round-trip),
  validation (range, integer, past-slot, missing slot, non-object,
  missing timestamps), independent multi-hour scheduling, and
  re-toggle replacement. 417 tests total (was 414).

1 files changed, 21 insertions, 2 deletions

diff --git a/packages/core/src/db/index.ts b/packages/core/src/db/index.ts
index 29448bc..93ec1f9 100644
--- a/packages/core/src/db/index.ts
+++ b/packages/core/src/db/index.ts
@@ -54,9 +54,28 @@ export function getDatabase(): Database {
 		updated_at        INTEGER NOT NULL
 	)`);
 
+	// Wake schedule: 4 rows per marked hour (one per :00 / :15 / :30 / :45 probe
+	// slot). The PK is (hour, slot_minute). Destructive migration off the legacy
+	// single-row-per-hour schema: detect by absence of the `slot_minute` column
+	// and drop the old table. Other tables (credentials, api_keys, usage_cache,
+	// settings, tabs, chunks) are NOT touched.
+	const legacyWakeSchema = (() => {
+		try {
+			const cols = _db.query("PRAGMA table_info(wake_schedule)").all() as Array<{ name: string }>;
+			if (cols.length === 0) return false; // table doesn't exist yet
+			return !cols.some((c) => c.name === "slot_minute");
+		} catch {
+			return false;
+		}
+	})();
+	if (legacyWakeSchema) {
+		_db.run("DROP TABLE IF EXISTS wake_schedule");
+	}
 	_db.run(`CREATE TABLE IF NOT EXISTS wake_schedule (
-		hour         INTEGER PRIMARY KEY CHECK (hour BETWEEN 0 AND 23),
-		next_wake_at INTEGER NOT NULL
+		hour         INTEGER NOT NULL CHECK (hour BETWEEN 0 AND 23),
+		slot_minute  INTEGER NOT NULL CHECK (slot_minute IN (0, 15, 30, 45)),
+		next_wake_at INTEGER NOT NULL,
+		PRIMARY KEY (hour, slot_minute)
 	)`);
 
 	_db.run(`CREATE TABLE IF NOT EXISTS usage_cache (