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/files.rs

@@ -275,14 +275,14 @@ pub async fn list_photos<TagD: TagDao, FS: FileSystemAccess>(
     // Resolve the optional library filter. Unknown values return 400. A
     // `None` result means "union across all libraries" and downstream
     // walks iterate every configured library root.
-    let library = match crate::libraries::resolve_library_param(&app_state, req.library.as_deref())
-    {
-        Ok(lib) => lib,
-        Err(msg) => {
-            log::warn!("Rejecting /photos request: {}", msg);
-            return HttpResponse::BadRequest().body(msg);
-        }
-    };
+    let library =
+        match crate::libraries::resolve_library_param_state(&app_state, req.library.as_deref()) {
+            Ok(lib) => lib,
+            Err(msg) => {
+                log::warn!("Rejecting /photos request: {}", msg);
+                return HttpResponse::BadRequest().body(msg);
+            }
+        };
 
     let span_context = opentelemetry::Context::current_with_span(span);
 
@@ -1238,7 +1238,7 @@ pub async fn list_exif_summary(
     // Resolve the library filter up front so a bad id/name 400s before we
     // ever take the DAO mutex. None == union across all libraries.
     let library_filter =
-        match crate::libraries::resolve_library_param(&app_state, req.library.as_deref()) {
+        match crate::libraries::resolve_library_param_state(&app_state, req.library.as_deref()) {
             Ok(lib) => lib.map(|l| l.id),
             Err(msg) => {
                 span.set_status(Status::error(msg.clone()));