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/config/validation.ts

@@ -10,6 +10,7 @@ import {
 } from "../plugins/config-state.js";
 import { loadPluginManifestRegistry } from "../plugins/manifest-registry.js";
 import { validateJsonSchemaValue } from "../plugins/schema-validator.js";
+import { hasKind } from "../plugins/slots.js";
 import {
   hasAvatarUriScheme,
   isAvatarDataUrl,
@@ -847,7 +848,7 @@ function validateConfigObjectWithPluginsBase(
         enabled = false;
         reason = memoryDecision.reason;
       }
-      if (memoryDecision.selected && record.kind === "memory") {
+      if (memoryDecision.selected && hasKind(record.kind, "memory")) {
         selectedMemoryPluginId = pluginId;
       }
     }