feat: nightly agentic pre-generation of memory reels

Implement end-to-end nightly pre-generation of memory reels with agentic
scripting that grounds narration in calendar, location, messages, and RAG.

Sections A-E from the plan:

A. Extract produce_reel pipeline core from run_reel_job with
   ScripterMode::Fast/Agentic and progress callbacks.

B. Agentic scripter: factor run_readonly_tool_loop from the insight
   generator, build read-only tool gate, prompt builder with GPS, and
   generate_script_agentic with fallback to fast path.

C. Precomputed reels ledger (SQLite table + DAO), GET /reels/precomputed
   handler with validity gate, GET /reels/by-key/{key}/video streaming,
   and normalize_library_key helper.

D. Nightly scheduler: spawn_pregen_scheduler with configurable hour,
   run_pregen_batch (day/week/month spans), pregen_one with dedup and
   disk-check, secs_until_next_run_hour time math.

E. user_ai_prefs passive mirror table + DAO for param capture in
   create_reel_handler and replay in the scheduler.

Also fixes resolve_library_param signature to take &[Library] and adds
resolve_library_param_state wrapper for AppState callers.

New files: migrations/2026-06-13-000000_add_precomputed_reels/,
  migrations/2026-06-13-000010_add_user_ai_prefs/,
  src/database/precomputed_reel_dao.rs,
  src/database/user_ai_prefs_dao.rs

src/main.rs

@@ -267,6 +267,25 @@ fn main() -> std::io::Result<()> {
             }
         }
 
+        // Spawn the nightly pre-generation scheduler (Section D).
+        {
+            use crate::database::{
+                InsightDao, SqliteInsightDao, SqliteUserAiPrefsDao, UserAiPrefsDao,
+            };
+
+            let insight_dao: Arc<Mutex<Box<dyn InsightDao>>> =
+                Arc::new(Mutex::new(Box::new(SqliteInsightDao::new())));
+            let prefs_dao: Arc<Mutex<Box<dyn UserAiPrefsDao>>> =
+                Arc::new(Mutex::new(Box::new(SqliteUserAiPrefsDao::new())));
+
+            reels::spawn_pregen_scheduler(
+                app_state.clone(),
+                web::Data::new(insight_dao),
+                web::Data::new(prefs_dao),
+            )
+            .await;
+        }
+
         HttpServer::new(move || {
             let user_dao = SqliteUserDao::new();
             let favorites_dao = SqliteFavoriteDao::new();
@@ -348,6 +367,8 @@ fn main() -> std::io::Result<()> {
                 .service(reels::create_reel_handler)
                 .service(reels::reel_status_handler)
                 .service(reels::reel_video_handler)
+                .service(reels::precomputed_reel_handler)
+                .service(reels::precomputed_video_handler)
                 .service(ai::generate_insight_handler)
                 .service(ai::generate_agentic_insight_handler)
                 .service(ai::generation_status_handler)