feat: server-side override pause/resume for builtin adapter types

Replace the client-side-only override store with a real server-side
toggle. When a developer pauses the external override, the server swaps
ALL adapter behavior back to the builtin — execute handler, model listing,
config schema, detection — not just the UI parser.

Server changes:
- registry.ts: builtinFallbacks map + pausedOverrides set + setOverridePaused()
- routes/adapters.ts: PATCH /api/adapters/:type/override endpoint + overridePaused in list

UI changes:
- adapters.ts: setOverridePaused API method + overridePaused on AdapterInfo
- AdapterManager: overrideMutation calls server, instant feedback via invalidate()
- use-disabled-adapters.ts: reads adapter.overridePaused from server response

Removed:
- disabled-overrides-store.ts: no longer needed (server is the source of truth)

Note: already-running agent sessions keep the adapter they started with.
Only new sessions use the swapped adapter.

ui/src/adapters/disabled-overrides-store.ts

@@ -1,90 +0,0 @@
-/**
- * Client-side store for disabled external adapter overrides.
- *
- * When an external adapter overrides a builtin type, the user may want to
- * pause the override (use the builtin parser) without hiding the type from
- * menus entirely.  This is separate from the server's per-type `disabled`
- * flag which controls menu visibility.
- *
- * Persisted to localStorage so it survives page reloads.
- *
- * Implements the React external store pattern (subscribe/getSnapshot)
- * so that components using useSyncExternalStore re-render on changes.
- */
-
-const STORAGE_KEY = "paperclip:disabled-overrides";
-
-let disabledOverrides = new Set<string>();
-
-// ── React external store plumbing ────────────────────────────────────
-
-/** Monotonically increasing version — changes on every mutation. */
-let snapshotVersion = 0;
-
-const listeners = new Set<() => void>();
-
-/** Subscribe to store changes (for useSyncExternalStore). */
-export function subscribeToOverrides(callback: () => void): () => void {
-  listeners.add(callback);
-  return () => listeners.delete(callback);
-}
-
-/**
- * Return a value that changes whenever the store changes.
- * React compares this with Object.is to decide whether to re-render.
- */
-export function getOverridesSnapshot(): number {
-  return snapshotVersion;
-}
-
-function emitChange(): void {
-  snapshotVersion++;
-  for (const fn of listeners) fn();
-}
-
-// ── Public API ───────────────────────────────────────────────────────
-
-/** Check if the external override for a builtin type is paused. */
-export function isOverrideDisabled(type: string): boolean {
-  return disabledOverrides.has(type);
-}
-
-/** Pause or resume an external override. */
-export function setOverrideDisabled(type: string, disabled: boolean): void {
-  if (disabled) {
-    disabledOverrides.add(type);
-  } else {
-    disabledOverrides.delete(type);
-  }
-  persist();
-  emitChange();
-}
-
-/** Get all types with paused overrides (sync read). */
-export function getDisabledOverrides(): Set<string> {
-  return disabledOverrides;
-}
-
-// ── Persistence ──────────────────────────────────────────────────────
-
-function persist(): void {
-  try {
-    localStorage.setItem(STORAGE_KEY, JSON.stringify([...disabledOverrides]));
-  } catch {
-    // localStorage unavailable — no-op
-  }
-}
-
-function hydrate(): void {
-  try {
-    const raw = localStorage.getItem(STORAGE_KEY);
-    if (raw) {
-      disabledOverrides = new Set(JSON.parse(raw));
-    }
-  } catch {
-    // corrupt or unavailable — start empty
-  }
-}
-
-// Hydrate on module load
-hydrate();

ui/src/adapters/use-disabled-adapters.ts

@@ -1,8 +1,7 @@
-import { useEffect, useMemo, useSyncExternalStore } from "react";
+import { useEffect, useMemo } from "react";
 import { useQuery } from "@tanstack/react-query";
 import { adaptersApi } from "@/api/adapters";
 import { setDisabledAdapterTypes } from "@/adapters/disabled-store";
-import { isOverrideDisabled, subscribeToOverrides, getOverridesSnapshot } from "@/adapters/disabled-overrides-store";
 import { syncExternalAdapters } from "@/adapters/registry";
 import { queryKeys } from "@/lib/queryKeys";
 
@@ -24,10 +23,6 @@ export function useDisabledAdaptersSync(): Set<string> {
     staleTime: 5 * 60 * 1000,
   });
 
-  // Subscribe to the client-side override store so that
-  // syncExternalAdapters() re-runs when overrides are toggled.
-  useSyncExternalStore(subscribeToOverrides, getOverridesSnapshot);
-
   // Eagerly register external adapter types in the UI registry so that
   // consumers calling listUIAdapters() in the same render cycle see them.
   // This is idempotent — already-registered types are skipped.
@@ -39,7 +34,7 @@ export function useDisabledAdaptersSync(): Set<string> {
           type: a.type,
           label: a.label,
           disabled: a.disabled,
-          overrideDisabled: a.overriddenBuiltin ? isOverrideDisabled(a.type) : undefined,
+          overrideDisabled: a.overridePaused,
         })),
     );
   }