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/database/models.rs

@@ -38,7 +38,13 @@ impl InsightJobStatus {
             "completed" => Self::Completed,
             "failed" => Self::Failed,
             "cancelled" => Self::Cancelled,
-            _ => Self::Failed,
+            other => {
+                log::warn!(
+                    "Unknown InsightJobStatus value: {:?}, treating as failed",
+                    other
+                );
+                Self::Failed
+            }
         }
     }
 }
@@ -224,6 +230,13 @@ pub struct InsertPhotoInsight {
     /// inserted before the hash is available stay null and the
     /// reconciliation pass backfills them.
     pub content_hash: Option<String>,
+    pub num_ctx: Option<i32>,
+    pub temperature: Option<f32>,
+    pub top_p: Option<f32>,
+    pub top_k: Option<i32>,
+    pub min_p: Option<f32>,
+    pub system_prompt: Option<String>,
+    pub persona_id: Option<String>,
 }
 
 #[derive(Serialize, Queryable, Clone, Debug)]
@@ -243,6 +256,13 @@ pub struct PhotoInsight {
     pub backend: String,
     pub fewshot_source_ids: Option<String>,
     pub content_hash: Option<String>,
+    pub num_ctx: Option<i32>,
+    pub temperature: Option<f32>,
+    pub top_p: Option<f32>,
+    pub top_k: Option<i32>,
+    pub min_p: Option<f32>,
+    pub system_prompt: Option<String>,
+    pub persona_id: Option<String>,
 }
 
 // --- Libraries ---