refactor(cron): rename scheduler feature to cron

Rename the recurring-jobs feature scheduler->cron to disambiguate from the
legacy ScheduledRun system (/api/scheduled), which is left untouched:

- ScheduledJob->CronJob, SchedulerService->CronService
- /api/scheduler/jobs -> /api/cron/jobs; SSE scheduler:* -> cron:*
- state keys cronJobs/cronJobRuns
- files moved to src/cron/, cron-routes.ts, cron-port.ts, types/cron.ts
- frontend cron-ui.js, #cronModal, menu "Cron"
- docs moved to docs/cron-discovery.md + docs/cron-build-brief.md, README guides
- new tests: cron-service.test.ts, cron-time.test.ts

Green: tsc, lint, frontend-syntax, format, 30 cron + 9 legacy scheduled-runs tests.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PmvZR12aX2v8K7YhqxPUAU

src/types/cron.ts

@@ -0,0 +1,94 @@
+/**
+ * @fileoverview Cron Jobs type definitions.
+ *
+ * NOTE: This is intentionally distinct from the existing `ScheduledRun` concept
+ * (see src/web/ports/infra-port.ts), which is a run-now, duration-bounded
+ * autonomous loop. A `CronJob` is a SAVED, NAMED job with a recurring
+ * schedule (once/interval/daily/weekly), enable/disable, next-run calculation,
+ * and a history of `CronJobRun` records. The two do not interact.
+ *
+ * Persisted to `~/.codeman/state.json` via StateStore (see AppState).
+ */
+
+import type { SessionMode } from './session.js';
+
+/** How a job's fire times are computed. */
+export type ScheduleType = 'once' | 'interval' | 'daily' | 'weekly';
+
+/** Where the prompt text comes from. */
+export type PromptMode = 'inline_text' | 'prompt_file_path';
+
+/** How the prompt is delivered into the session. */
+export type InputMode = 'paste' | 'typed';
+
+/** Lifecycle status of a single job execution. */
+export type CronJobRunStatus = 'created' | 'session_started' | 'prompt_sent' | 'failed';
+
+/** What triggered a run. */
+export type TriggerType = 'scheduled' | 'manual_run_now';
+
+/** What to do for an AUTOMATIC run when sessions of the same agent already exist. */
+export type ConcurrencyPolicy = 'warn_only' | 'skip_if_same_agent_running';
+
+/**
+ * A saved, named cron job.
+ */
+export interface CronJob {
+  id: string;
+  name: string;
+  /** Reuses Codeman's existing session modes; 'shell' covers Terminal/custom. */
+  agentType: SessionMode;
+  workingDir: string;
+  /** Optional custom launch command (only meaningful for 'shell' mode). */
+  launchCommand?: string;
+
+  promptMode: PromptMode;
+  promptText?: string;
+  promptFilePath?: string;
+  inputMode: InputMode;
+
+  scheduleType: ScheduleType;
+  /** once: absolute epoch-ms fire time. */
+  runAt?: number;
+  /** interval: minutes between fires. */
+  intervalMinutes?: number;
+  /** daily: 'HH:MM' (24h, server-local time). */
+  dailyTime?: string;
+  /** weekly: weekdays 0–6 (0=Sunday). */
+  weeklyDays?: number[];
+  /** weekly: 'HH:MM' (24h, server-local time). */
+  weeklyTime?: string;
+
+  enabled: boolean;
+  notes?: string;
+  /** Applies to automatic (scheduled) runs only. Manual Run Now always warns client-side. */
+  concurrencyPolicy: ConcurrencyPolicy;
+
+  // ── Bookkeeping (server-maintained) ─────────────────────────────────────
+  createdAt: number;
+  updatedAt: number;
+  lastRunAt: number | null;
+  nextRunAt: number | null;
+  lastStatus: CronJobRunStatus | null;
+  /** Duplicate-launch guard: identifies the most recent due-time consumed. */
+  lastDueKey: string | null;
+  /** True once a 'once' job has fired (it is also disabled). */
+  completedOnce?: boolean;
+}
+
+/**
+ * A single execution of a cron job (history record).
+ */
+export interface CronJobRun {
+  id: string;
+  cronJobId: string;
+  sessionId: string | null;
+  sessionName: string | null;
+  startedAt: number;
+  finishedAt: number | null;
+  status: CronJobRunStatus;
+  errorMessage?: string;
+  triggerType: TriggerType;
+  /** Best-effort deep link to the created session in the web UI. */
+  createdSessionUrl: string | null;
+}