test: add E2E integration tests for cross-platform notifications

Add comprehensive E2E-style integration tests for notification commands
that verify command structure without executing system APIs. This approach
enables testing cross-platform code in Linux CI environments.

Changes:
- Add 10 E2E tests for notification command structure verification
- Add helper functions to build commands for testing (Linux, Windows)
- Test command arguments, quote escaping, unicode support, edge cases
- Fix flaky frontend test by mocking console.error in config store test
- Fix lint errors (unused variables, TypeScript any types, unused imports)
- Fix TypeScript type errors in Svelte components

Test coverage:
- notifications.rs: 10 new E2E tests (command structure verification)
- All 417 backend tests passing
- All 363 frontend tests passing (no stderr output)
- 61.08% backend coverage (appropriate for architecture)

The E2E tests verify:
✓ Correct command names and arguments
✓ Proper quote escaping for PowerShell
✓ Unicode preservation across platforms
✓ Special character handling
✓ Edge case resilience (empty inputs)
✓ Cross-platform consistency

✨ This commit was crafted with love by Hikari~ 🌸

src/lib/components/SessionHistoryPanel.svelte

@@ -17,8 +17,21 @@
   let isImporting = $state(false);
   let showClearAllConfirm = $state(false);
 
-  const sessions = $derived(sessionsStore.sessions);
-  const isLoading = $derived(sessionsStore.isLoading);
+  let sessions = $state<SessionListItem[]>([]);
+  let isLoading = $state(false);
+
+  $effect(() => {
+    const unsubSessions = sessionsStore.sessions.subscribe((value) => {
+      sessions = value;
+    });
+    const unsubLoading = sessionsStore.isLoading.subscribe((value) => {
+      isLoading = value;
+    });
+    return () => {
+      unsubSessions();
+      unsubLoading();
+    };
+  });
 
   onMount(() => {
     sessionsStore.loadSessions();
@@ -303,11 +316,11 @@
       </div>
 
       <div class="overflow-y-auto flex-1">
-        {#if $isLoading}
+        {#if isLoading}
           <div class="flex items-center justify-center p-8">
             <div class="text-[var(--text-tertiary)]">Loading sessions...</div>
           </div>
-        {:else if $sessions.length === 0}
+        {:else if sessions.length === 0}
           <div class="flex flex-col items-center justify-center p-8 text-center">
             <svg
               class="w-16 h-16 text-[var(--text-tertiary)] mb-4"
@@ -329,7 +342,7 @@
           </div>
         {:else}
           <div class="divide-y divide-[var(--border-color)]">
-            {#each $sessions as session (session.id)}
+            {#each sessions as session (session.id)}
               <div class="p-4 hover:bg-[var(--bg-secondary)] transition-colors group">
                 <div class="flex items-start justify-between gap-4">
                   <button class="flex-1 text-left" onclick={() => handleViewSession(session)}>
@@ -451,7 +464,6 @@
 </div>
 
 {#if showClearAllConfirm}
-  <!-- svelte-ignore a11y_no_static_element_interactions -->
   <div
     class="fixed inset-0 bg-black/50 backdrop-blur-sm z-[60] flex items-center justify-center p-4"
     onclick={() => (showClearAllConfirm = false)}
@@ -459,7 +471,6 @@
     tabindex="0"
     onkeydown={(e) => e.key === "Escape" && (showClearAllConfirm = false)}
   >
-    <!-- svelte-ignore a11y_no_static_element_interactions a11y_click_events_have_key_events -->
     <div
       class="bg-[var(--bg-primary)] border border-red-500/30 rounded-lg shadow-xl max-w-md w-full p-6"
       onclick={(e) => e.stopPropagation()}