security: fix vulnerabilities 1-7 from security audit

- Fix #1: Share handler IDOR - enforce owner check on share operations
- Fix #2: list_files_query IDOR - bind folder queries to authenticated user
- Fix #3: Dedup handler IDOR - restrict dedup operations to file owner
- Fix #4: Trash handler OptionalAuthUser - require full AuthUser
- Fix #5: Error info leakage - sanitize 500 error responses
- Fix #6: Chunked upload IDOR - bind upload sessions to user_id,
  add verify_session_owner() check on all session operations
- Fix #7: CSP unsafe-inline removal - migrate all inline scripts,
  styles and event handlers to external files, tighten CSP to
  script-src 'self'; style-src 'self'

New files:
  - static/js/core/theme-init.js (render-blocking theme init)
  - static/js/core/sw-register.js (service worker registration)
  - static/css/views/device-verify.css (extracted inline styles)
  - static/js/views/device-verify/device-verify.js (extracted inline script)

src/interfaces/api/handlers/search_handler.rs

@@ -74,7 +74,7 @@ impl SearchHandler {
                 error!("Search error: {}", err);
                 (
                     StatusCode::INTERNAL_SERVER_ERROR,
-                    Json(json!({ "error": format!("Search error: {}", err) })),
+                    Json(json!({ "error": "Search error" })),
                 )
                     .into_response()
             }
@@ -115,7 +115,7 @@ impl SearchHandler {
                 error!("Search error: {}", err);
                 (
                     StatusCode::INTERNAL_SERVER_ERROR,
-                    Json(json!({ "error": format!("Search error: {}", err) })),
+                    Json(json!({ "error": "Search error" })),
                 )
                     .into_response()
             }
@@ -159,7 +159,7 @@ impl SearchHandler {
                 error!("Suggestions error: {}", err);
                 (
                     StatusCode::INTERNAL_SERVER_ERROR,
-                    Json(json!({ "error": format!("Suggestions error: {}", err) })),
+                    Json(json!({ "error": "Suggestions error" })),
                 )
                     .into_response()
             }
@@ -195,7 +195,7 @@ impl SearchHandler {
                 error!("Error clearing search cache: {}", err);
                 (
                     StatusCode::INTERNAL_SERVER_ERROR,
-                    Json(json!({ "error": format!("Error clearing search cache: {}", err) })),
+                    Json(json!({ "error": "Error clearing search cache" })),
                 )
                     .into_response()
             }