feat: add server control commands (disable, enable, destroy)

Add /lsp-servers, /lsp-disable, /lsp-enable, and /lsp-destroy TUI commands.
Disabled servers are tracked in-memory per-extension-instance; the shared
daemon is never mutated by disable/enable. When all servers are disabled,
LSP tools are removed from the active tool set so the LLM won't attempt them.

Also adds a destroy_server daemon operation that kills running LspClient
entries by server ID or all entries.

src/daemon.ts

@@ -191,6 +191,24 @@ async function handle(req: DaemonRequest): Promise<DaemonResponse> {
         };
         return { id: req.id, ok: true, result };
       }
+      case "destroy_server": {
+        // Manual Kill - Evict entries matching the server ID (or all if
+        // unspecified). This is explicitly destructive; the caller knows
+        // what it's doing.
+        const toDestroy = req.serverId
+          ? Array.from(entries.values()).filter(
+              (e) => e.server.id === req.serverId,
+            )
+          : Array.from(entries.values());
+        for (const entry of toDestroy) {
+          evict(entry, "manual destroy");
+        }
+        return {
+          id: req.id,
+          ok: true,
+          result: { destroyed: toDestroy.map((e) => e.key) },
+        };
+      }
       case "shutdown": {
         // Acknowledge first, then tear down on next tick so the response
         // has a chance to flush before we close listeners.