feat(ai-chat): agent write tools, provenance wiring, chat panel + provider settings UI" -m "Backend:

- Add reversible write tools to the per-user agent toolset (page create/update/
  move/soft-delete; comment reply + resolve), exposed under the user's JWT and
  enforced by Docmost CASL; no permanent/force delete (D3).
- Non-spoofable agent provenance: sign actor/aiChatId into the access and collab
  tokens (TokenService), propagate via jwt.strategy onto the request, and set
  pages.last_updated_source/last_updated_ai_chat_id on REST create/update/move and
  comments.created_source/resolved_source/ai_chat_id.
- packages/mcp: add an optional getCollabToken provider (content-edit provenance)
  and guard against empty tokens; service-account /mcp path unchanged.

Frontend:
- Admin 'AI / Models' settings section: provider/model/embedding/base URL, a
  write-only API key field, system prompt, and Test connection.
- AI chat panel (useChat + DefaultChatTransport): conversation list, streamed
  messages, tool-call action log and page citations; header entry point gated on
  settings.ai.chat.

Compile-verified (server nest build + client tsc/vite); not yet live-tested.
Known gaps: history 'AI agent' badge (C3), vector RAG (D), external MCP (E);
chat tool-card citation links pending a fix.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/server/src/common/decorators/auth-provenance.decorator.ts

@@ -0,0 +1,27 @@
+import { createParamDecorator, ExecutionContext } from '@nestjs/common';
+
+/**
+ * The agent-edit provenance carried by the request, read from the SIGNED access
+ * token (set by `jwt.strategy`). `actor` is 'agent' only for the internal AI
+ * agent's minted token; every normal user request resolves to 'user'. Because
+ * it comes from the signed claim — never a client body field — a normal user
+ * cannot fake an 'agent' marker.
+ */
+export interface AuthProvenanceData {
+  actor: 'user' | 'agent';
+  aiChatId: string | null;
+}
+
+/**
+ * Resolve the request's provenance. Defaults to a 'user' actor when the claim
+ * is absent (e.g. an endpoint reached without going through the access-token
+ * strategy path), so callers can always set the marker unconditionally.
+ */
+export const AuthProvenance = createParamDecorator(
+  (data: unknown, ctx: ExecutionContext): AuthProvenanceData => {
+    const request = ctx.switchToHttp().getRequest();
+    const actor = request?.raw?.actor === 'agent' ? 'agent' : 'user';
+    const aiChatId = request?.raw?.aiChatId ?? null;
+    return { actor, aiChatId };
+  },
+);