feat: add Plugin and MCP Server Management panels

Backend (Rust):
- Add plugin management commands: list, install, uninstall, enable, disable, update
- Add MCP server management commands: list, get details, remove
- Integrate with Claude CLI's 'plugin' and 'mcp' subcommands
- Export PluginInfo and McpServerInfo types

Frontend (Svelte):
- Create PluginManagementPanel component with full CRUD operations
- Create McpManagementPanel component with server listing and removal
- Add buttons to StatusBar for both panels
- Beautiful UI with lucide-svelte icons
- Theme-aware styling using CSS variables
- Real-time loading states and error handling

Closes #133
Closes #134

src/lib/components/StatusBar.svelte

@@ -27,6 +27,8 @@
   import GitPanel from "./GitPanel.svelte";
   import ProfilePanel from "./ProfilePanel.svelte";
   import AgentMonitorPanel from "./AgentMonitorPanel.svelte";
+  import PluginManagementPanel from "./PluginManagementPanel.svelte";
+  import McpManagementPanel from "./McpManagementPanel.svelte";
   import { conversationsStore } from "$lib/stores/conversations";
   import {
     generateContextInjection,
@@ -54,6 +56,8 @@
   let showGitPanel = $state(false);
   let showProfile = $state(false);
   let showAgentMonitor = $state(false);
+  let showPluginPanel = $state(false);
+  let showMcpPanel = $state(false);
   let isSummarising = $state(false);
   const progress = $derived($achievementProgress);
   const activeAgentCount = $derived($runningAgentCount);
@@ -468,6 +472,34 @@
         />
       </svg>
     </button>
+    <button
+      onclick={() => (showPluginPanel = true)}
+      class="p-1 text-gray-500 icon-trans-hover"
+      title="Plugin Management"
+    >
+      <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="M20 7l-8-4-8 4m16 0l-8 4m8-4v10l-8 4m0-10L4 7m8 4v10M4 7v10l8 4"
+        />
+      </svg>
+    </button>
+    <button
+      onclick={() => (showMcpPanel = true)}
+      class="p-1 text-gray-500 icon-trans-hover"
+      title="MCP Server Management"
+    >
+      <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="M5 12h14M5 12a2 2 0 01-2-2V6a2 2 0 012-2h14a2 2 0 012 2v4a2 2 0 01-2 2M5 12a2 2 0 00-2 2v4a2 2 0 002 2h14a2 2 0 002-2v-4a2 2 0 00-2-2m-2-4h.01M17 16h.01"
+        />
+      </svg>
+    </button>
     <button
       onclick={toggleEditor}
       disabled={connectionStatus !== "connected"}
@@ -704,3 +736,11 @@
 {#if showAgentMonitor}
   <AgentMonitorPanel isOpen={showAgentMonitor} onClose={() => (showAgentMonitor = false)} />
 {/if}
+
+{#if showPluginPanel}
+  <PluginManagementPanel onClose={() => (showPluginPanel = false)} />
+{/if}
+
+{#if showMcpPanel}
+  <McpManagementPanel onClose={() => (showMcpPanel = false)} />
+{/if}