feat(scheduler): add cron-style scheduled jobs (backend)

Adds a saved/named scheduling layer on top of Codeman's existing session
primitives. Distinct from the legacy run-now ScheduledRun concept.

- types/scheduler.ts: ScheduledJob + ScheduledJobRun
- state-store: persist scheduledJobs/scheduledJobRuns in ~/.codeman/state.json
- scheduler/scheduler-time.ts: pure once/interval/daily/weekly next-run math
- scheduler/scheduler-service.ts: CRUD, Run Now, due-checker tick, run history;
  reuses SessionPort (create -> start -> writeViaMux) for launches
- web/routes/scheduler-routes.ts: /api/scheduler/jobs CRUD + run + history
- web/schemas.ts: zod validation with schedule-type-aware refinements
- web/sse-events.ts: scheduler:* events
- server.ts: wire service into route context + 30s background tick loop
- test/scheduler-time.test.ts: 14 unit tests for next-run calculations

Phase 1 discovery recorded in SCHEDULER_DISCOVERY.md.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Rp7JhmQXcYJhmxFMdZuuah

src/config/server-timing.ts

@@ -51,6 +51,19 @@ export const SCHEDULED_CLEANUP_INTERVAL = 5 * 60 * 1000;
 /** Completed scheduled run max age before cleanup (ms) */
 export const SCHEDULED_RUN_MAX_AGE = 60 * 60 * 1000;
 
+// ============================================================================
+// Scheduled Jobs (cron-style scheduler)
+// ============================================================================
+
+/** How often the scheduler loop wakes to check for due jobs (ms). */
+export const SCHEDULER_TICK_INTERVAL = 30 * 1000;
+
+/** Max attempts (× 500ms) to poll a launched session for CLI readiness before sending the prompt. */
+export const SCHEDULER_READY_MAX_ATTEMPTS = 60;
+
+/** Extra settle delay after CLI readiness is detected, before sending the prompt (ms). */
+export const SCHEDULER_READY_SETTLE_MS = 2000;
+
 /** Session limit retry wait before retrying (ms) */
 export const SESSION_LIMIT_WAIT_MS = 5000;