docs: consolidate MCP coverage into a single canonical guide

[danielmeppiel]

Context: Surfaced via #122 and the followup conversation with @lirantal -- MCP coverage is spread across 24 doc pages with declaration syntax duplicated 3x and trust model duplicated 2x. There is no canonical MCP Servers guide. Result: users with the universal mcp.json / Claude Desktop / Cursor mental model can't find the answer and bounce.

Audit numbers (verified):

• 44 MCP mentions in integrations/ide-tool-integration.md (declaration syntax buried inside an "IDE integration" page)
• 26 in guides/dependencies.md (duplicate declaration syntax)
• 17 in reference/manifest-schema.md (third copy)
• 8 in enterprise/security.md (duplicate trust model)
• Plus 20 other pages with passing mentions

Asymmetry: Skills, Prompts, Plugins each have a dedicated guide page. MCP does not. That gap is the structural reason for the discoverability failure.

Proposed change (consolidate, don't add)

+1 page: docs/src/content/docs/guides/mcp-servers.md

Sidebar slot: under Guides, between Plugins and Dependencies & Lockfile -- the missing primitive guide.

Outline:

• Overview + table comparing registry-backed vs self-defined
• Quick start: add a one-off MCP server (the lirantal-shaped section, top of page)
  • Side-by-side: mcp.json / Claude Desktop block -> APM equivalent
  • The exact command + args snippet
  • One-liner CLI: apm install --mcp NAME -- COMMAND ARGS... (references shipped CLI from [link-to-w3-issue])
• Registry-backed servers (name, overlays, version pinning)
• Self-defined servers -- stdio / http / sse / streamable-http
  • Common mistakes: command: "npx pkg" anti-pattern (references shipped warn from [link-to-w4-issue])
• Trust model (canonical home; other pages deep-link here)
• Governance / policies (1 paragraph + deep-link)
• IDE behavior (1 paragraph + deep-link)
• CLI commands (tight list + deep-links)
• Schema reference (deep-link)

-3 sections shrink:

1. integrations/ide-tool-integration.md MCP section: ~150 -> ~30 lines (IDE-specific writeout behavior only)
2. guides/dependencies.md MCP Formats section: ~50 -> ~20 lines (summary + deep-link)
3. enterprise/security.md MCP trust model: drop duplication, deep-link to new guide

Sync: packages/apm-guide/.apm/skills/apm-usage/dependencies.md -- terse mirror of the new guide (per repo doc-sync rule).

Net effect: +1 page (~250 lines), -200 lines from duplicates = +50 lines net. Adds canonical surface; reduces total MCP content.

Anti-patterns to avoid:

• Don't add three separate pages (sprawl trap)
• Don't add a new sidebar section for MCP (reuse Guides)
• Don't grow ide-tool-integration.md further

Scope

• New page (doc-writer)
• Three section shrinks (doc-writer)
• Skill sync (doc-writer + doc-sync rule check)
• Cross-link audit + updates (doc-analyser)
• Sidebar update in docs/astro.config.mjs
• SEO/meta polish (oss-growth-hacker)
• Local docs build verification (no broken links)

Sequencing: Sequential after [link-to-w3-issue] so Quick Start can reference the shipped apm install --mcp CLI without "coming soon" placeholders.

Workstream: Part of #122 followup.