fix: schema init, duplicate routes, and image preview bugs

- Move pg_trgm extension creation before CalDAV indexes that depend on it
- Remove duplicate app-password route registration that caused panic
- Fix missing comma in language selector array (Dutch entry)
- Await async canEdit() in file click handler (Promise was always truthy)
- Detect images by extension fallback when mime_type is octet-stream
  (files uploaded via Nextcloud WebDAV API lack correct mime types)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/common/config.rs

@@ -238,7 +238,7 @@ impl Default for DatabaseConfig {
     fn default() -> Self {
         Self {
             // Updated connection string with default credentials that PostgreSQL often uses
-            connection_string: "postgres://postgres:postgres@localhost:5439/oxicloud".to_string(),
+            connection_string: "postgres://postgres:postgres@localhost:5432/oxicloud".to_string(),
             max_connections: 20,
             min_connections: 5,
             connect_timeout_secs: 10,