feat(persona-chat): continue an SMS thread with a persona

Persona conversations can now be anchored on a message in an SMS thread.
Creating one snapshots the thread up to that message (via SMS-API) into the
row; every turn appends it to the persona prompt with guidance to talk like a
text thread rather than write an insight.

Anchored turns get four tools: get_thread_messages (page the thread),
look_at_message_image (local vision on an MMS photo), get_photos_near_time
(library photos with tags and people) and look_at_photo (local vision on a
library photo). The conversation list filters by contact_id.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/database/mod.rs

@@ -64,7 +64,7 @@ pub use knowledge_dao::{
     KnowledgeDao, PersonaFilter, RecentActivity, SqliteKnowledgeDao,
 };
 pub use location_dao::{LocationHistoryDao, SqliteLocationHistoryDao};
-pub use persona_dao::{ImportPersona, PersonaDao, PersonaPatch, SqlitePersonaDao};
+pub use persona_dao::{ImportPersona, PersonaDao, PersonaPatch, SmsAnchor, SqlitePersonaDao};
 pub use precomputed_reel_dao::{PrecomputedReelDao, SqlitePrecomputedReelDao};
 pub use preview_dao::{PreviewDao, SqlitePreviewDao};
 pub use search_dao::{SearchHistoryDao, SqliteSearchHistoryDao};