fix: restore permission modal reactivity by replacing array mutation with new array creation

Previously, pendingPermissions was mutated in-place via .push(), causing
Svelte's reactivity chain to potentially receive the same array reference
and skip re-rendering the PermissionModal. Switching to spread syntax
guarantees a new reference on every update.

Also removed $state() from PermissionModal's local variables to match
the Svelte 4 reactive pattern used by other working components (Terminal),
avoiding rune-mode signal equality short-circuits.

src/lib/components/PermissionModal.svelte

@@ -9,10 +9,10 @@
   import { conversationsStore } from "$lib/stores/conversations";
   import { configStore } from "$lib/stores/config";
 
-  let permissions: PermissionRequest[] = $state([]);
+  let permissions: PermissionRequest[] = [];
   let selectedPermissions = new SvelteSet<string>();
-  let grantedToolsList: string[] = $state([]);
-  let workingDirectory = $state("");
+  let grantedToolsList: string[] = [];
+  let workingDirectory = "";
 
   conversationsStore.pendingPermissions.subscribe((perms) => {
     permissions = perms;