Fix agentic reel audit issues: midnight bug, DAO wiring, dead code, DST timezone, validation

Blocking fixes:
- secs_until_next_run_hour: same-hour now returns 0 instead of 24h
- capture_prefs: called at both handler return points, never fails request
- capture_prefs: resolves library param, upserts to user_ai_prefs via DAO
- Scheduler: uses AppState DAOs instead of separate connections
- Pregen dedup: uses resolved library param instead of hardcoded 'all'
- run_readonly_tool_loop: added #[allow(dead_code)] (used in main.rs only)
- run_readonly_tool_loop: removed dead messages.push() call
- InsightGenerator: added exif_dao() getter for scheduler reuse

Medium fixes:
- Input validation: run_hour clamped 0-23, week_dow clamped 0-6
- DST-sensitive timezone: fixed_tz_offset() with env var config

Low fixes:
- Documented REEL_PREGEN_MAX_TOOL_ITERS and REEL_PREGEN_TZ_FIXED_MINUTES
- Removed dead test_app_state function and unused imports

Also fix: UpsertUserAiPrefs import path, chrono::Local::with_ymd_and_hms
requires TimeZone trait + .single(), unwrap_or_else closure simplification

src/main.rs

@@ -268,23 +268,7 @@ 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;
-        }
+        reels::spawn_pregen_scheduler(app_state.clone()).await;
 
         HttpServer::new(move || {
             let user_dao = SqliteUserDao::new();