feat(mcp): plugin-carried Connect-an-agent Setup page + nav (#2714)

[os-zhuang]

#2714 Phase 1, companion to objectstack-ai/objectui#2372 (which closesobjectstack-ai/objectui#2363).

The MCP plugin now carries its own Setup surface — CONNECT_AGENT_UI_BUNDLE (page connect_agent + nav entry under Integrations) registered on kernel:ready via the manifest service, the exact pattern of the marketplace pages (cloud ADR-0009: the nav lives and dies with the capability). Gated on isMcpServerEnabled(): an opted-out deployment gets no page and no nav entry, mirroring the 404'd surface.

The page body is the mcp:connect-agent SDUI widget (objectui#2372): environment MCP URL from /discovery, per-client connect cards (claude.ai/Desktop, Claude Code + official plugin, Cursor deeplink, VS Code, Codex), SKILL.md download (#2728), show-once API-key minting. zh-CN nav label (连接智能体) added alongside the existing Setup nav translations.

Verification

• mcp 66 ✓ (2 new: bundle registered by default with correct page/nav shape; nothing registered when opted out)
• Browser-verified end-to-end with the live widget (console Vite dev → showcase server): nav entry renders under Integrations, page loads with all six cards and the real env URL, an API key minted on-page drives a real MCP tools/list (9 tools), SKILL.md link serves the env-customized markdown.

Refs #2714.

🤖 Generated with Claude Code

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Project	Deployment	Actions	Updated (UTC)
spec	Canceled		Jul 10, 2026 4:24am

[github-actions]

📓 Docs Drift Check

This PR changes 2 package(s): @objectstack/mcp, @objectstack/platform-objects.

10 hand-written doc(s) reference the affected code and may need an implementation-accuracy re-verification:

• content/docs/ai/actions-as-tools.mdx(via @objectstack/mcp)
• content/docs/ai/agents.mdx(via @objectstack/mcp)
• content/docs/ai/index.mdx(via @objectstack/mcp)
• content/docs/ai/natural-language-queries.mdx(via @objectstack/mcp)
• content/docs/api/index.mdx(via @objectstack/mcp)
• content/docs/deployment/environment-variables.mdx(via @objectstack/mcp)
• content/docs/plugins/packages.mdx(via @objectstack/mcp, @objectstack/platform-objects)
• content/docs/protocol/knowledge.mdx(via @objectstack/mcp)
• content/docs/releases/implementation-status.mdx(via @objectstack/mcp)
• content/docs/ui/setup-app.mdx(via @objectstack/platform-objects)

Advisory only. To re-verify, run the docs-accuracy-audit workflow scoped to these files:
node scripts/docs-audit/affected-docs.mjs origin/main → pass the list as args.docs.