fix: register dedup response returns full existing file metadata (not zeros)

src/api/server.rs

@@ -1370,14 +1370,32 @@ async fn register_single_file(
         .await
         {
             tracing::info!("[REGISTER] Content hash collision → already registered: {}", existing_uuid);
-            let existing_name: Option<String> = sqlx::query_scalar(
-                &format!("SELECT file_name FROM {} WHERE file_uuid = $1", videos_table)
+            let existing_info: Option<(String, String, f64, i32, i32, f64, i64, Option<String>)> = sqlx::query_as(
+                &format!("SELECT file_name, file_path, duration, width, height, fps, total_frames, registration_time::text FROM {} WHERE file_uuid = $1", videos_table)
             ).bind(&existing_uuid).fetch_optional(db.pool()).await.unwrap_or(None);
+            if let Some((ename, epath, dur, w, h, f, tf, rt)) = existing_info {
+                return RegisterFileResponse {
+                    success: true,
+                    file_uuid: existing_uuid,
+                    file_name: ename,
+                    file_path: epath.clone(),
+                    file_type: None,
+                    duration: dur,
+                    width: w as u32,
+                    height: h as u32,
+                    fps: f,
+                    total_frames: tf as u64,
+                    registration_time: rt,
+                    already_exists: true,
+                    message: format!("Content already registered: {}", epath),
+                };
+            }
+            // Fallback: content_hash matched but full info query failed
             return RegisterFileResponse {
                 success: true,
                 file_uuid: existing_uuid,
-                file_name: existing_name.unwrap_or(file_name),
-                file_path: canonical_path,
+                file_name: file_name.clone(),
+                file_path: canonical_path.clone(),
                 file_type: None,
                 duration: 0.0,
                 width: 0,