fix: support multi-kind plugins for dual slot ownership (#57507) (thanks @fuller-stack-dev)

* feat(plugins): support multi-kind plugins for dual slot ownership

* fix: address review feedback on multi-kind plugin support

- Use sorted normalizeKinds() for kind-mismatch comparison in loader.ts
  (fixes order-sensitive JSON.stringify for arrays)
- Derive slot-to-kind reverse mapping from SLOT_BY_KIND in slots.ts
  (removes hardcoded ternary that would break for future slot types)
- Use shared hasKind() helper in config-state.ts instead of inline logic

* fix: don't disable dual-kind plugin that still owns another slot

When a new plugin takes over one slot, a dual-kind plugin that still
owns the other slot must not be disabled — otherwise context engine
resolution fails at runtime.

* fix: exempt dual-kind plugins from memory slot disablement

A plugin with kind: ["memory", "context-engine"] must stay enabled even
when it loses the memory slot, so its context engine role can still load.

* fix: address remaining review feedback

- Pass manifest kind (not hardcoded "memory") in early memory gating
- Extract kindsEqual() helper for DRY kind comparison in loader.ts
- Narrow slotKeyForPluginKind back to single PluginKind with JSDoc
- Reject empty array in parsePluginKind
- Add kindsEqual tests

* fix: use toSorted() instead of sort() per lint rules

* plugins: include default slot ownership in disable checks and gate dual-kind memory registration

src/plugins/manifest.ts

@@ -24,7 +24,7 @@ export type PluginManifest = {
   legacyPluginIds?: string[];
   /** Provider ids that should auto-enable this plugin when referenced in auth/config/models. */
   autoEnableWhenConfiguredProviders?: string[];
-  kind?: PluginKind;
+  kind?: PluginKind | PluginKind[];
   channels?: string[];
   providers?: string[];
   /** Cheap startup activation lookup for plugin-owned CLI inference backends. */
@@ -233,6 +233,16 @@ export function resolvePluginManifestPath(rootDir: string): string {
   return path.join(rootDir, PLUGIN_MANIFEST_FILENAME);
 }
 
+function parsePluginKind(raw: unknown): PluginKind | PluginKind[] | undefined {
+  if (typeof raw === "string") {
+    return raw as PluginKind;
+  }
+  if (Array.isArray(raw) && raw.length > 0 && raw.every((k) => typeof k === "string")) {
+    return raw.length === 1 ? (raw[0] as PluginKind) : (raw as PluginKind[]);
+  }
+  return undefined;
+}
+
 export function loadPluginManifest(
   rootDir: string,
   rejectHardlinks = true,
@@ -282,7 +292,7 @@ export function loadPluginManifest(
     return { ok: false, error: "plugin manifest requires configSchema", manifestPath };
   }
 
-  const kind = typeof raw.kind === "string" ? (raw.kind as PluginKind) : undefined;
+  const kind = parsePluginKind(raw.kind);
   const enabledByDefault = raw.enabledByDefault === true;
   const legacyPluginIds = normalizeStringList(raw.legacyPluginIds);
   const autoEnableWhenConfiguredProviders = normalizeStringList(