fix: audit fixes for async insight jobs + persist generation params

- Fix query param mismatch: rename GenerationStatusQuery.file_path to
  path so the client's app-resume buildQuery({ path: ... }) resolves
  correctly instead of always getting 400
- Remove dead _lib_id bindings from both generate handlers
- Return 202 Accepted instead of 200 from generate endpoints
- Restore OpenTelemetry span instrumentation on generate handlers
- Remove stale UNIQUE constraint from initial migration (incompatible
  with plain-INSERT DAO)
- Add tests for status guard: complete_job/fail_job are no-ops when
  job is already cancelled, and cancel_job by id
- Persist generation params (num_ctx, temperature, top_p, top_k, min_p,
  system_prompt, persona_id) on the photo_insights table for auditing

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/ai/mod.rs

@@ -19,11 +19,11 @@ pub use daily_summary_job::{
     generate_daily_summaries, strip_summary_boilerplate,
 };
 pub use handlers::{
-    chat_history_handler, chat_rewind_handler, chat_stream_handler, chat_turn_handler,
-    delete_insight_handler, export_training_data_handler, generate_agentic_insight_handler,
-    generate_insight_handler, generation_status_handler, get_all_insights_handler,
-    get_available_models_handler, get_insight_handler, get_openrouter_models_handler,
-    rate_insight_handler,
+    cancel_generation_handler, chat_history_handler, chat_rewind_handler, chat_stream_handler,
+    chat_turn_handler, delete_insight_handler, export_training_data_handler,
+    generate_agentic_insight_handler, generate_insight_handler, generation_status_handler,
+    get_all_insights_handler, get_available_models_handler, get_insight_handler,
+    get_openrouter_models_handler, rate_insight_handler,
 };
 pub use insight_generator::InsightGenerator;
 pub use llamacpp::LlamaCppClient;