feat(maestro): live directory autocomplete in spawn form (NAP-329)

Adds api.listDir + a reusable dirAutocomplete widget (live dropdown,
Tab/Enter completion, /-drill-in, per-(daemon,dir) cache) wired onto the
cwd and worktree base-repo fields, with matching dropdown styling.

web/src/api.ts

@@ -1,4 +1,11 @@
-import type { ApiError, CreateSessionRequest, DaemonInfo, Session, Uuid } from "./types.js";
+import type {
+  ApiError,
+  CreateSessionRequest,
+  DaemonInfo,
+  DirListing,
+  Session,
+  Uuid,
+} from "./types.js";
 
 async function jsonOrError<T>(res: Response): Promise<T> {
   if (res.ok) {
@@ -43,6 +50,14 @@ export async function killSession(id: Uuid): Promise<void> {
   );
 }
 
+/** List one directory's immediate subdirectories on `daemonId`'s host (NAP-329).
+ * `path` may be empty, `~`, relative, or absolute — the daemon resolves it
+ * against its own home dir. */
+export async function listDir(daemonId: string, path: string): Promise<DirListing> {
+  const url = `/api/daemons/${encodeURIComponent(daemonId)}/dirs?path=${encodeURIComponent(path)}`;
+  return jsonOrError(await fetch(url, { credentials: "same-origin" }));
+}
+
 export function eventsWsUrl(): string {
   const proto = location.protocol === "https:" ? "wss:" : "ws:";
   return `${proto}//${location.host}/api/events`;