perf(draft): optimize memory layout by removing double indirection & implemented optimistic locking via Arc::ptr_eq for with_data_modify (#5942)

* perf(draft): optimize memory layout by removing double indirection

- Replace `Arc<Box<T>>` with `Arc<T>` to reduce pointer chasing and memory overhead.
- Leverage `Arc::from(Box<T>)` in async modify path for efficient ownership transfer.
- Fix race conditions in `edit_draft` by ensuring atomicity under write lock.
- Performance improved by ~16-24% across all operations (based on Criterion bench).

Benchmarks:
- latest_arc:     41.1ns (-24.2%)
- edit_draft:     92.2ns (-17.6%)
- apply:          89.8ns (-17.7%)
- async_modify:   66.0ns (-16.6%)

* perf(draft): implemented optimistic locking via Arc::ptr_eq for with_data_modify

Benchmarks confirm only a negligible ~2% (1.3ns) overhead for async operations, ensuring total data integrity during concurrent updates.

src-tauri/src/enhance/mod.rs

@@ -106,7 +106,7 @@ async fn get_config_values() -> ConfigValues {
         ref verge_http_enabled,
         ref enable_dns_settings,
         ..
-    } = **verge_arc;
+    } = *verge_arc;
 
     let (clash_core, enable_tun, enable_builtin, socks_enabled, http_enabled, enable_dns_settings) = (
         Some(verge_arc.get_valid_clash_core()),