feat: MCP server + in-repo skills (agent-friendly platform) (#2269)

* feat(api): support global API key from config.yaml (api.global_api_key)

Accept a config-defined global API key anywhere a web-UI key is accepted
(X-API-Key / Bearer), with no login session and no DB record. Useful for
automated deployments and AI agents (HTTP API + MCP). Defaults to empty
(disabled); does not require the lbk_ prefix.

- templates/config.yaml: add api.global_api_key with security notes
- service/apikey.py: verify_api_key checks global key first (constant-time)
- docs/API_KEY_AUTH.md: document the global key + security guidance
- tests: cover global-key match, prefix-free, fallback-to-db, disabled

* feat(mcp): expose LangBot management as an MCP server at /mcp

Add an MCP (Model Context Protocol) server so external AI agents can manage a
LangBot instance. Reuses the same API-key auth as the HTTP API (including the
config.yaml global API key).

- pkg/api/mcp/server.py: FastMCP server wrapping the service layer; 21 curated
  tools across system/bots/pipelines/models/knowledge/mcp-servers/skills
- pkg/api/mcp/mount.py: ASGI dispatcher fronting Quart; authenticates /mcp
  requests with an API key, runs the streamable-HTTP session manager lifespan
- controller/main.py: serve the wrapped ASGI app via hypercorn (was run_task)
- web: new 'MCP' tab in the API integration dialog showing endpoint, auth, and
  client config; i18n for 8 locales
- tests/manual/mcp_smoke.py: e2e check (401 unauth, list tools, call tools)

Tool surface is intentionally curated (not all ~25 route groups) to keep the
agent surface small, safe, and maintainable. Extend deliberately.

* feat(skills): add in-repo skills/ as the single source of truth

Migrate the agent skills + QA/e2e test harness from the (now archived)
langbot-app/langbot-skills repo into LangBot/skills/, and add four new skills.

Migrated:
- langbot-plugin-dev, langbot-testing (e2e), langbot-env-setup,
  langbot-skills-maintenance, langbot-eba-adapter-dev
- the bin/lbs CLI (src/, test/, scripts/, schemas/, qa-agent-docs/)

New:
- langbot-dev      core backend + web development
- langbot-deploy   Docker/K8s deployment + config.yaml + global API key
- langbot-mcp-ops  operating the LangBot MCP server (/mcp)
- langbot-space-ops operating the Space marketplace MCP server

- src/cli.ts repoRoot(): recognize the skills assets root (skills.index.json +
  bin/lbs) so the CLI works when nested inside the LangBot repo
- README.md: unified skill catalog; skills.index.json regenerated

Parity with source verified: bin/lbs validate + node test suite match the
source repo (only the uncommitted .lbpkg build-artifact fixture differs).

* docs(agents): document agent-facing surfaces + API/MCP/skills sync rule

* docs(readme): add 'Built for AI Agents' section across all locales

Highlight MCP server, in-repo skills (single source of truth), AGENTS.md
sync rule, and llms.txt. Cross-link LangBot Space MCP marketplace.

* style(mcp): fix ruff format + prettier lint in MCP server and API panel

* style(web): prettier format MCP i18n locale entries

* docs(skills): note MCP instance control in dev/testing skills

All development-guidance skills now point to the LangBot instance MCP
server (/mcp) and the Space marketplace MCP server, reusing API keys.

docs/API_KEY_AUTH.md

@@ -10,6 +10,38 @@ API keys can be managed through the web interface:
 2. Click the "API Keys" button at the bottom of the sidebar
 3. Create, view, copy, or delete API keys as needed
 
+## Global API Key (config.yaml)
+
+In addition to web-UI-created keys (stored in the database, prefixed `lbk_`),
+LangBot supports a **global API key** defined directly in `data/config.yaml`.
+This is useful for automated deployments, infrastructure-as-code, and AI agents
+that need API/MCP access **without a login session and without creating a
+database record first**.
+
+```yaml
+api:
+    port: 5300
+    # ...
+    global_api_key: 'your-strong-secret-here'   # leave empty to disable
+```
+
+Behavior:
+
+- When `api.global_api_key` is a non-empty string, that exact value is accepted
+  anywhere a normal API key is accepted — the `X-API-Key` header or
+  `Authorization: Bearer <key>` — across the HTTP service API **and the MCP
+  server**.
+- The global key does **not** require the `lbk_` prefix; use any sufficiently
+  strong secret.
+- Leave it empty (`''`, the default) to disable it entirely; only database-backed
+  `lbk_` keys will then be accepted.
+- Existing installs are unaffected until you add the key — config completion only
+  backfills top-level keys, and the lookup is defensive when the field is absent.
+
+> **Security:** the global key is stored in plaintext in `config.yaml`. Only
+> enable it on trusted/internal deployments, keep the file permissions tight,
+> always serve over HTTPS, and rotate the value if it may have leaked.
+
 ## Using API Keys
 
 ### Authentication Headers