feat: add ENABLE_CLAUDEAI_MCP_SERVERS opt-out setting

Adds a toggle in the MCP Servers settings section to control whether
Claude Code connects to MCP servers configured in Claude.ai. When
disabled, sets ENABLE_CLAUDEAI_MCP_SERVERS=false. Also fixes a
pre-existing omission of disable_cron from the TypeScript HikariConfig
interface.

Closes #210

src/lib/components/ConfigSidebar.svelte

@@ -60,6 +60,7 @@
     disable_1m_context: false,
     disable_cron: false,
     include_git_instructions: true,
+    enable_claudeai_mcp_servers: true,
     max_output_tokens: null,
     trusted_workspaces: [],
     background_image_path: null,
@@ -562,8 +563,8 @@
           <span class="text-sm text-[var(--text-primary)]">Disable cron scheduling</span>
         </label>
         <p class="text-xs text-[var(--text-tertiary)] mt-1 ml-7">
-          Sets <code class="font-mono">CLAUDE_CODE_DISABLE_CRON=1</code> to prevent Claude from
-          scheduling recurring tasks
+          Sets <code class="font-mono">CLAUDE_CODE_DISABLE_CRON=1</code> to prevent Claude from scheduling
+          recurring tasks
         </p>
       </div>
 
@@ -658,6 +659,22 @@
           class="w-full px-3 py-2 bg-[var(--bg-primary)] border border-[var(--border-color)] rounded-lg text-[var(--text-primary)] font-mono text-sm focus:outline-none focus:border-[var(--accent-primary)] resize-none"
         ></textarea>
       </div>
+
+      <!-- Enable Claude.ai MCP Servers -->
+      <div class="mb-4">
+        <label class="flex items-center gap-3 cursor-pointer">
+          <input
+            type="checkbox"
+            bind:checked={config.enable_claudeai_mcp_servers}
+            class="w-4 h-4 rounded border-[var(--border-color)] bg-[var(--bg-primary)] text-[var(--accent-primary)] focus:ring-[var(--accent-primary)]"
+          />
+          <span class="text-sm text-[var(--text-primary)]">Enable Claude.ai MCP servers</span>
+        </label>
+        <p class="text-xs text-[var(--text-tertiary)] mt-1 ml-7">
+          When disabled, sets <code class="font-mono">ENABLE_CLAUDEAI_MCP_SERVERS=false</code> to prevent
+          Claude Code from connecting to MCP servers configured in Claude.ai.
+        </p>
+      </div>
     </section>
 
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