feat: add local-first private AI digest workflow

Migrate app code into canonical feature slices, add phone-only AI digest scheduling and review, wire local notification/background task support, and cover the flow with tests.

docs/SETUP.md

@@ -75,6 +75,38 @@ Behavior notes:
   permission prompts
 - tapping a reminder notification opens reminder management UI in-app
 
+## Phone-Only Private AI Digest
+
+The app can run without a production backend by keeping `USE_FAKE_BACKEND=true`
+and using the LLM integration only for a private weekly digest.
+
+Digest behavior:
+
+- relationship data remains local-first in the Hive/shared-preferences store
+- scheduled digest payloads use pseudonymous tokens such as `person_001`
+- names, aliases, sender names, source URLs, raw shared text, and sensitive
+  notes are not sent in the scheduled digest prompt
+- LLM results are saved as pending AI review drafts first
+- accepting a draft creates a local idea, task, or reminder
+- dismissing a draft leaves existing local data unchanged
+
+Scheduling:
+
+- default cadence is weekly
+- default run window is Sunday 21:00
+- default policy is Wi-Fi + charging
+- iOS background execution is best-effort because the OS controls exact timing
+- Settings includes `Run Private Digest Now` for physical-phone debug builds
+
+iOS setup now includes:
+
+- `UIBackgroundModes`: `fetch`, `processing`
+- `BGTaskSchedulerPermittedIdentifiers`: `com.relationshipsaver.llm.digest`
+- Workmanager registration in `AppDelegate.swift`
+
+Local notifications are used for the digest-ready alert. No APNs/FCM remote
+push payload is required.
+
 ## WhatsApp Share Intake (MVP)
 
 Inbound WhatsApp share-intake is now wired behind a listener in the authenticated