feat(ag-ui): FakeAgent for offline cockpit demo (#140)

* docs: AG-UI FakeAgent implementation plan

5 tasks: implement FakeAgent + spec, provideFakeAgUiAgent + spec,
public-api exports, cockpit demo rewiring, verify + PR.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* feat(ag-ui): FakeAgent + provideFakeAgUiAgent for offline demos

In-process AbstractAgent subclass that emits a canned streaming
response. Drop-in replacement for provideAgUiAgent({ url }) when
no real backend is available. Tests cover event ordering, token
streaming, and unsubscribe cancellation.

Deviation from plan: FakeAgent.run() is public (not protected) to
satisfy AbstractAgent's public abstract signature in @ag-ui/client@0.0.53.
Spec calls agent.run() directly rather than via (agent as any).run().

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* feat(cockpit): wire AG-UI streaming demo to FakeAgent

Demo runs end-to-end with no backend or network. Real-backend wiring
is one line away via provideAgUiAgent({ url: ... }).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* chore: override rxjs version to dedupe @ag-ui/client's nested install

@ag-ui/client@0.0.52 pins rxjs@7.8.1 exactly, which caused npm to
install rxjs in two locations (top-level 7.8.2 and nested 7.8.1
under node_modules/@ag-ui/client/). TypeScript saw the two Observable
types as incompatible across module boundaries when the AG-UI adapter
tried to subscribe to source.agent().

The npm override forces all rxjs resolutions to follow the project's
~7.8.0 range, deduping to a single hoisted install. ABI-compatible.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* fix: preserve cross-platform swc bindings in lockfile after rxjs override

Previous commit (43ad74f) regenerated package-lock.json on macOS,
which silently dropped optional platform-specific @next/swc-* bindings
for non-darwin platforms. CI on Linux failed with 'Failed to load
native binding' on apps/cockpit/next.config.ts and apps/website/.

Restore main's lockfile then surgically remove only the nested
@ag-ui/client/node_modules/rxjs entry (the override target). Verified:
all 24 @next/swc-* entries present, single hoisted rxjs, npm ci passes
on clean checkout.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

Author: blove

cockpit/ag-ui/streaming/angular/src/app/app.config.ts

@@ -1,10 +1,17 @@
 // SPDX-License-Identifier: PolyForm-Noncommercial-1.0.0
 import { ApplicationConfig } from '@angular/core';
-import { provideAgUiAgent } from '@cacheplane/ag-ui';
-import { environment } from '../environments/environment';
+import { provideFakeAgUiAgent } from '@cacheplane/ag-ui';
 
 export const appConfig: ApplicationConfig = {
   providers: [
-    provideAgUiAgent({ url: environment.agUiUrl }),
+    provideFakeAgUiAgent({
+      tokens: [
+        'This', ' is', ' the', ' AG-UI', ' streaming', ' demo.',
+        ' Messages', ' are', ' generated', ' in-process', ' by', ' a', ' FakeAgent',
+        ' that', ' emits', ' canned', ' AG-UI', ' events.',
+        ' Swap', ' to', ' provideAgUiAgent({ url })', ' to', ' connect', ' a', ' real', ' backend.',
+      ],
+      delayMs: 50,
+    }),
   ],
 };