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/insight_generator.rs

@@ -1432,6 +1432,13 @@ impl InsightGenerator {
             backend: "local".to_string(),
             fewshot_source_ids: None,
             content_hash: None,
+            num_ctx,
+            temperature,
+            top_p,
+            top_k,
+            min_p,
+            system_prompt: custom_system_prompt.clone(),
+            persona_id: None,
         };
 
         let mut dao = self.insight_dao.lock().expect("Unable to lock InsightDao");
@@ -4176,6 +4183,13 @@ Return ONLY the summary, nothing else."#,
             backend: kind.as_str().to_string(),
             fewshot_source_ids: fewshot_source_ids_json,
             content_hash: None,
+            num_ctx,
+            temperature,
+            top_p,
+            top_k,
+            min_p,
+            system_prompt: custom_system_prompt.clone(),
+            persona_id: Some(persona_id.clone()),
         };
 
         let stored = {