feat(agents): smoke tests + README + docs (Stage 6, final)

Closes the agents feature.

Smoke tests (run via `pnpm test:smoke` against a live mcpd at
$MCPD_URL, default https://mcpctl.ad.itaz.eu):

* tests/smoke/agent.smoke.test.ts — full CRUD round-trip:
  create secret + Llm + agent with sampling defaults; `get agents`
  surfaces it; `get agent foo -o yaml | apply -f` round-trips
  identically; create + list a thread via the HTTP API; agent delete
  leaves Llm + secret intact (Restrict + SetNull as designed). Self-
  skips with a warning when /healthz is unreachable.

* tests/smoke/agent-chat.smoke.test.ts — gated on
  MCPCTL_SMOKE_LLM_URL + MCPCTL_SMOKE_LLM_KEY. Provisions secret +
  Llm + agent against a real upstream, runs `mcpctl chat -m … --no-
  stream` (asserts a reply lands), then runs the streaming default
  (asserts text on stdout + `(thread: …)` on stderr). The fast path
  for verifying the in-cluster qwen3-thinking deployment:

      MCPCTL_SMOKE_LLM_URL=http://litellm.nvidia-nim.svc.cluster.local:4000/v1 \
      MCPCTL_SMOKE_LLM_MODEL=qwen3-thinking \
      MCPCTL_SMOKE_LLM_KEY=$(pulumi config get --stack homelab \
        secrets:litellmMcpctlGatewayToken) \
        pnpm test:smoke

Docs:

* README.md — new "Agents" section under Resources with the
  qwen3-thinking quickstart and links to docs/agents.md and
  docs/chat.md. Adds llm + agent rows to the resources table.

* docs/agents.md (new) — full reference: data model, chat-parameter
  table, HTTP API, RBAC mapping, tool-use loop semantics, yaml
  round-trip shorthand, the kubernetes-deployment wiring recipe,
  and a troubleshooting section (namespace collision, llm-in-use,
  pending-row recovery, Anthropic-tool limitation).

* docs/chat.md (new) — user-facing `mcpctl chat` walkthrough:
  modes, per-call flags, slash-commands, threads, and a
  troubleshooting section.

* CLAUDE.md — adds a "Resource types" cheatsheet with one-line
  pointers to each, including the new `agent` row that links to
  the docs.

All suites still green: mcpd 759/759, mcplocal 715/715, cli 430/430.
Smoke tests typecheck and self-skip when no live mcpd is reachable.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -494,11 +494,58 @@ new FileCache('ns', { maxSize: '10%' })     // 10% of partition
 | **secret** | Key-value credentials | API tokens, passwords |
 | **template** | Reusable server blueprint | Community server configs |
 | **project** | Workspace grouping servers | "monitoring", "home-automation" |
+| **llm** | Server-managed LLM provider | OpenAI / Anthropic / vLLM endpoint + key |
+| **agent** | LLM persona pinned to one Llm | "I review security; ask after each major change" |
 | **prompt** | Curated content for Claude | Instructions, docs, guides |
 | **promptrequest** | Pending prompt proposal | LLM-submitted, needs approval |
 | **rbac** | Access control bindings | Who can do what |
 | **serverattachment** | Server-to-project link | Virtual resource for `apply` |
 
+## Agents
+
+An **Agent** is an LLM persona — a pinned `Llm`, a system prompt, an optional
+project attach, and LiteLLM-style sampling defaults. Once attached to a
+project, the agent inherits the project's prompts (merged into its system
+block, sorted by priority) and gets to call the project's MCP servers as
+tools during chat.
+
+Every agent is also exposed back to MCP clients as a virtual server named
+`agent-<name>` with one tool `chat`. So another Claude session connecting to
+the same project sees, e.g., `agent-reviewer/chat` in `tools/list` with the
+description "I review security design — ask me after each major change."
+That's how agents consult each other.
+
+```bash
+# 1) point at an LLM. For your in-cluster qwen3-thinking via LiteLLM:
+mcpctl create secret litellm-key --data API_KEY=sk-…
+mcpctl create llm qwen3-thinking \
+  --type openai \
+  --model qwen3-thinking \
+  --url http://litellm.nvidia-nim.svc.cluster.local:4000/v1 \
+  --api-key-ref litellm-key/API_KEY
+
+# 2) create an agent, pinned to that Llm and attached to a project
+mcpctl create agent reviewer \
+  --llm qwen3-thinking \
+  --project mcpctl-dev \
+  --description "I review security design — ask me after each major change." \
+  --system-prompt-file ./prompts/reviewer.md \
+  --default-temperature 0.2 --default-max-tokens 4096
+
+# 3) chat with it (interactive REPL — Ctrl-D to exit)
+mcpctl chat reviewer
+
+# Or one-shot
+mcpctl chat reviewer -m "Look at PR #42 and tell me what's risky."
+
+# Resume a thread
+mcpctl get threads --agent reviewer
+mcpctl chat reviewer --thread <id>
+```
+
+Full reference: [docs/agents.md](docs/agents.md). User-facing chat guide:
+[docs/chat.md](docs/chat.md).
+
 ## Commands
 
 ```bash