Fix: Update button remaining disabled in transaction edit mode

This commit resolves an issue where the Update button in the transaction form
would remain disabled when attempting to edit a transaction. The problem was
in how the transactionStore was managing state updates during transaction editing.

Key changes:
- Enhanced startEditingTransaction function in transactionStore.ts to ensure proper reactivity
- Added clean copy creation of transaction objects to avoid reference issues
- Implemented a state update cycle with null value first to force reactivity
- Added a small timeout to ensure state changes are properly detected by components

The Transaction form now correctly enables the Update button when in edit mode,
regardless of account selection state.

astro.config.mjs

@@ -15,9 +15,13 @@ export default defineConfig({
   vite: {
     resolve: {
       alias: {
-        'react-dom/server': 'react-dom/server',
-        'react-dom/server.browser': 'react-dom/server',
+        // Use the browser version of react-dom/server for client-side rendering
+        'react-dom/server.browser': 'react-dom/cjs/react-dom-server.browser.production.min.js',
       },
     },
+    // Prevent server-only modules from being bundled for client side
+    ssr: {
+      noExternal: ['react-dom/server'],
+    },
   },
 });