feat: add git integration panel

- Add Rust backend for git operations (status, diff, branches, commit, push, pull, fetch, stage, unstage, discard, create branch)
- Add GitPanel.svelte component with three tabs: Changes, Branches, History
- Integrate git button into StatusBar with link icon
- Use consistent accent color theming for buttons

src/lib/components/StatusBar.svelte

@@ -20,6 +20,7 @@
   import KeyboardShortcutsModal from "./KeyboardShortcutsModal.svelte";
   import { achievementProgress } from "$lib/stores/achievements";
   import SessionHistoryPanel from "./SessionHistoryPanel.svelte";
+  import GitPanel from "./GitPanel.svelte";
 
   const DISCORD_URL = "https://chat.nhcarrigan.com";
   const DONATE_URL = "https://donate.nhcarrigan.com";
@@ -35,6 +36,7 @@
   let showHelp = $state(false);
   let showKeyboardShortcuts = $state(false);
   let showSessionHistory = $state(false);
+  let showGitPanel = $state(false);
   const progress = $derived($achievementProgress);
   let currentConfig: HikariConfig = $state({
     model: null,
@@ -233,6 +235,20 @@
         />
       </svg>
     </button>
+    <button
+      onclick={() => (showGitPanel = true)}
+      class="p-1 text-gray-500 hover:text-[var(--accent-primary)] transition-colors"
+      title="Git Panel"
+    >
+      <svg class="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+        <path
+          stroke-linecap="round"
+          stroke-linejoin="round"
+          stroke-width="2"
+          d="M13.828 10.172a4 4 0 00-5.656 0l-4 4a4 4 0 105.656 5.656l1.102-1.101m-.758-4.899a4 4 0 005.656 0l4-4a4 4 0 00-5.656-5.656l-1.1 1.1"
+        />
+      </svg>
+    </button>
     <button
       onclick={() => (showStats = !showStats)}
       class="p-1 text-gray-500 hover:text-[var(--accent-primary)] transition-colors {showStats
@@ -391,3 +407,7 @@
 {#if showSessionHistory}
   <SessionHistoryPanel onClose={() => (showSessionHistory = false)} />
 {/if}
+
+{#if showGitPanel}
+  <GitPanel isOpen={showGitPanel} onClose={() => (showGitPanel = false)} />
+{/if}