fix(admin): only block navigation/close when changes are unsaved

- Update beforeNavigate guard to check autosave status before blocking
- Allow instant navigation when status is 'saved' (no interruption)
- Add beforeunload warning for browser close/reload
- Only show warnings when status is NOT 'saved' (saving/error/idle)
- Improves UX by not interrupting users when everything is already saved

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/lib/components/admin/ProjectForm.svelte

@@ -177,9 +177,15 @@
 		}
 	})
 
-	// Navigation guard: flush autosave before navigating away
+	// Navigation guard: flush autosave before navigating away (only if there are unsaved changes)
 	beforeNavigate(async (navigation) => {
 		if (mode === 'edit' && hasLoaded && autoSave) {
+			// If status is 'saved', there are no unsaved changes - allow navigation
+			if (autoSave.status === 'saved') {
+				return
+			}
+
+			// Otherwise, flush any pending changes before navigating
 			navigation.cancel()
 			try {
 				await autoSave.flush()
@@ -191,6 +197,22 @@
 		}
 	})
 
+	// Warn before closing browser tab/window if there are unsaved changes
+	$effect(() => {
+		if (mode !== 'edit' || !autoSave) return
+
+		function handleBeforeUnload(event: BeforeUnloadEvent) {
+			// Only warn if there are unsaved changes
+			if (autoSave!.status !== 'saved') {
+				event.preventDefault()
+				event.returnValue = '' // Required for Chrome
+			}
+		}
+
+		window.addEventListener('beforeunload', handleBeforeUnload)
+		return () => window.removeEventListener('beforeunload', handleBeforeUnload)
+	})
+
 	// Keyboard shortcut: Cmd/Ctrl+S to save immediately
 	$effect(() => {
 		if (mode !== 'edit' || !autoSave) return