docs: dedicated 1-pagers for third-party tools (Bifrost, PAL, etc.) — link upstream docs + GitHub

[JacobPEvans]

Problem

Third-party tools currently get folded into other pages as subsections rather than getting their own page. The Bifrost gateway is the clearest example — it's a meaningful piece of the local AI stack with its own architecture, configuration surface, and operational concerns, but in #32 it landed as a "Local AI gateway" subsection of architecture/ai-pipeline instead of standing on its own.

A reader who wants to know "what is Bifrost, how do I set it up, where does it run" has to skim a different page that's primarily about something else.

Principles

1. Dedicated 1-pager per third-party tool worth mentioning. Match the existing per-tool format under security/tools/ (one page per secrets store). Same shape applies to: AI gateways, MCP coordinators, runner control planes, observability collectors, etc.
2. Lead with content sourced from the tool's own documentation homepage. Not copy-paste — adapt to this site's voice — but the upstream homepage is the canonical first source. Their maintainers know their tool better than we do.
3. ALWAYS link to the upstream homepage in the first paragraph or in a RepoMeta-style header. If it has a GitHub repo, link that too.
4. Reserve subsections of architecture/integration pages for how this tool fits our stack — not what the tool is. The architecture page explains the role; the dedicated page explains the tool.

Audit candidates

Tools currently referenced inline without dedicated pages:

Tool	Where mentioned today	Owner / link
Bifrost	architecture/ai-pipeline subsection (added in #32)	https://www.getmaxim.ai/bifrost / GitHub
PAL MCP	Same subsection	upstream repo
mermaid-cli	conventions/diagramming one-liner	https://github.com/mermaid-js/mermaid-cli
release-please	infrastructure/cicd/policy one-liner	https://github.com/googleapis/release-please
tf-summarize	infrastructure/cicd/overview + terraform-runs-on	https://github.com/dineshba/tf-summarize
tfcmt	infrastructure/terraform-check-placement	https://github.com/suzuki-shunsuke/tfcmt
trivy / checkov	infrastructure/terraform-check-placement	upstream sites
renovate	infrastructure/cicd/policy (presets reference)	https://www.mend.io/renovate
RunsOn	Has infrastructure/cicd/terraform-runs-on but the page is about our Terraform module — the tool RunsOn could use its own page	https://runs-on.com
direnv	infrastructure/overview and others	https://direnv.net
lefthook / pre-commit	implicit	https://github.com/evilmartians/lefthook

Not every entry needs a full page — some are footnotes — but the ones that drive non-trivial behavior in the stack (Bifrost, PAL, RunsOn-the-tool, renovate, tf-summarize) deserve their own pages.

Suggested first pass

Start with Bifrost since it triggered this:

• New page: tools/bifrost.mdx (or architecture/bifrost.mdx — pick based on where readers will look)
• Sections: What it is (sourced from upstream homepage), How it routes (our task-class → model mapping), How we run it (LaunchAgent, port, local-only mode), Where it sits in the pipeline (cross-link to architecture/ai-pipeline)
• Replace the current architecture/ai-pipeline#local-ai-gateway-bifrost subsection with a 2-paragraph summary + link to the dedicated page

Repeat for PAL MCP, then audit the table above in priority order.

Acceptance criteria

• tools/bifrost.mdx (or equivalent) exists with upstream homepage link in the first paragraph
• architecture/ai-pipeline references it instead of explaining Bifrost inline
• At least one other entry from the audit table also gets its own page in the same PR (PAL MCP is the natural pair)
• Style guide note added somewhere — likely conventions/overview or a new conventions/external-tools.mdx — codifying the "always link upstream docs + GitHub" rule so future pages don't drift

Refs

• Triggered by docs: migrate cross-repo standards from ai-assistant-instructions #32 (architecture/ai-pipeline.mdx change folding Bifrost in as a subsection)