feat: complete CalDAV (RFC 4791) and CardDAV (RFC 6352) implementation

- CalDAV: MKCALENDAR, PROPFIND, PUT/GET/DELETE events, REPORT calendar-query
- CardDAV: MKCOL, PROPFIND, PUT/GET/DELETE vCards, REPORT addressbook-query
- Fix routing: move CalDAV/CardDAV to top-level merge() with explicit routes
- Fix DB schema: VARCHAR(36) -> UUID for entity IDs, vcard_data -> vcard
- Fix 15 repository stub methods that returned empty results
- Fix vCard parser in ContactStorageAdapter (was hardcoded stub)
- All operations tested end-to-end in Docker (201/207/200/204 as expected)

src/interfaces/api/routes.rs

@@ -282,11 +282,8 @@ pub fn create_api_routes(app_state: &AppState) -> Router<AppState> {
         router = router.merge(webdav_handler::webdav_routes());
     }
     
-    // Add CalDAV routes
-    {
-        use crate::interfaces::api::handlers::caldav_handler;
-        router = router.nest("/caldav", caldav_handler::caldav_routes());
-    }
+    // NOTE: CalDAV and CardDAV routes are mounted at top-level (/caldav, /carddav)
+    // in main.rs for protocol compliance, NOT under /api.
 
     router
         .layer(CompressionLayer::new())