feat(v2): add SSH management, ctx integration, themes, detached mode, auto-updater

SSH session management:
- SshSession struct + ssh_sessions SQLite table in session.rs
- CRUD Tauri commands (ssh_session_list/save/delete) in lib.rs
- SshDialog.svelte (create/edit modal), SshSessionList.svelte (sidebar)
- SSH pane routes to TerminalPane with shell=/usr/bin/ssh + args

ctx context database integration:
- ctx.rs: read-only CtxDb (SQLITE_OPEN_READ_ONLY for ~/.claude-context/context.db)
- 5 Tauri commands (ctx_list_projects/get_context/get_shared/get_summaries/search)
- ContextPane.svelte with project selector, tabs, search
- ctx-bridge.ts adapter

Catppuccin theme flavors (Latte/Frappe/Macchiato/Mocha):
- themes.ts: all 4 palette definitions + buildXtermTheme/applyCssVariables
- theme.svelte.ts: reactive store with SQLite persistence
- SettingsDialog flavor dropdown, TerminalPane theme-aware

Detached pane mode (pop-out windows):
- detach.ts: isDetachedMode/getDetachedConfig from URL params
- App.svelte: conditional rendering of single pane without chrome

Other additions:
- Shiki syntax highlighting (highlight.ts, lazy singleton, 13 languages)
- Tauri auto-updater plugin (tauri-plugin-updater + updater.ts)
- AgentPane markdown rendering with Shiki code highlighting
- New deps: shiki, @tauri-apps/plugin-updater, tauri-plugin-updater

v2/src/lib/components/Layout/PaneContainer.svelte

@@ -5,10 +5,11 @@
     title: string;
     status?: 'idle' | 'running' | 'error' | 'done';
     onClose?: () => void;
+    onDetach?: () => void;
     children: Snippet;
   }
 
-  let { title, status = 'idle', onClose, children }: Props = $props();
+  let { title, status = 'idle', onClose, onDetach, children }: Props = $props();
 </script>
 
 <div class="pane-container">
@@ -18,6 +19,9 @@
       {#if status !== 'idle'}
         <span class="status {status}">{status}</span>
       {/if}
+      {#if onDetach}
+        <button class="detach-btn" onclick={onDetach} title="Pop out to new window">&#8599;</button>
+      {/if}
       {#if onClose}
         <button class="close-btn" onclick={onClose} title="Close pane">&times;</button>
       {/if}
@@ -75,6 +79,18 @@
   .status.error { color: var(--ctp-red); }
   .status.done { color: var(--ctp-green); }
 
+  .detach-btn {
+    background: none;
+    border: none;
+    color: var(--text-muted);
+    font-size: 12px;
+    cursor: pointer;
+    padding: 0 2px;
+    line-height: 1;
+  }
+
+  .detach-btn:hover { color: var(--ctp-blue); }
+
   .close-btn {
     background: none;
     border: none;