fix(programs): replace rolling-sweep monitor with passive watch + status panel

Tear out the 1-program-every-3s rolling sweep daemon (program_monitor.go); replace
with a passive watch that piggybacks on data the warmer already fetches. The Programs
page already has `latest_target_updated_at` for every program — use it.

How it works now:
- internal/api/program_watch.go: ProgramWatchOnRefresh(programs) is called from
  refreshProgramsCache after every catalogue rebuild. It scans
  latest_target_updated_at, fires one Discord alert per program whose timestamp
  exceeds the persisted watermark (settings key program_watch_latest_seen), then
  advances the watermark. Capped at 10 alerts/cycle to defeat one-time corpus shifts.
- BOOT INTRO: once per process (post-restart), sends a "📌 Scope watch ready —
  most recent update: X" message so the operator sees immediate confirmation the
  watch is alive. Removes the 1-hour "is it working?" black box.
- Programs page: new "Scope Update Watch" status card at the top showing daemon
  state, freshest update right now, watermark age, alerts this session, plus a
  🔔 Test webhook button (POST /api/scope/watch-test) that fires a sample Discord
  message instantly. No more "wait an hour to know if it works".
- GET /api/scope/watch-status powers the panel; POST /api/scope/watch-test does the
  manual delivery probe.

Webhook helper: utils.SendMonitorWebhookErr (returns delivery error) and
utils.MonitorWebhookConfigured added — SendMonitorWebhook keeps logging behavior.

Removed: program_monitor.go (272 lines), the boot StartProgramMonitor() call,
PROGRAM_MONITOR_SPACING_MS env, the full rolling-sweep cost model. The
program_assets table + RecordProgramScopeAssets stay (used by the one-shot reset
on previous boot); they're dormant going forward.

Verified: go build/vet/db+utils tests, node --check programs.js — all clean.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: h0tak88r

internal/api/api.go

@@ -581,6 +581,8 @@ func SetupAPI() *gin.Engine {
 		apiGroup.GET("/scope/platforms", apiScopePlatforms)
 		apiGroup.GET("/scope/programs", apiListPrograms)
 		apiGroup.POST("/scope/program-summaries", apiProgramScopeSummaries)
+		apiGroup.GET("/scope/watch-status", apiProgramWatchStatus)
+		apiGroup.POST("/scope/watch-test", apiProgramWatchTest)
 		// AI finding validation & reporting
 		apiGroup.POST("/findings/validate", apiValidateFinding)
 		apiGroup.POST("/findings/report", apiReportFinding)