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/daemonProtocol.ts

@@ -21,7 +21,8 @@ export type DaemonRequest =
     }
   | { id: number; op: "diagnostics"; file: string; timeoutMs?: number }
   | { id: number; op: "status" }
-  | { id: number; op: "shutdown" };
+  | { id: number; op: "shutdown" }
+  | { id: number; op: "destroy_server"; serverId?: string };
 
 export type DaemonRequestWithoutId =
   | {
@@ -32,7 +33,8 @@ export type DaemonRequestWithoutId =
     }
   | { op: "diagnostics"; file: string; timeoutMs?: number }
   | { op: "status" }
-  | { op: "shutdown" };
+  | { op: "shutdown" }
+  | { op: "destroy_server"; serverId?: string };
 
 // Response Shapes - Sent daemon -> client. `ok: true` carries result, else
 // `error` is a human-readable message string.