docs: generate real MCP tool reference pages

[hhimanshu]

Summary

Replaces the content/docs/api/mcp/index.mdx stub (which described a
different, now-removed tool crate) with a real generated reference for
the native MCP server's 66 tools.

• scripts/gen-mcp-docs.mjs reads a schema snapshot and writes one
  .mdx page per tool under content/docs/api/mcp/ — title, a plain-
  language summary, a parameters table, a returns table, and the full
  JSON Schema for both request and response.
• content/docs/api/mcp/index.mdx rewritten with real content: what
  the server is, how it's connected to (stdio), and a table of the 66
  tools grouped by area.
• content/docs/api/mcp/meta.json regenerated to list all 66 pages.
• npm run gen-mcp-docs added; CI gets a drift check mirroring the
  existing gen-docs/gen-openapi-docs pattern
  (git diff --exit-code -- content/docs/api/mcp).
• Closes Generate real MCP tool reference pages from the native command schema dump #132.

Fixed during independent verification (not in the original patch)

The tool descriptions in the source schema are Rust doc comments
written for the crate's own contributors — full of private-repo
references, internal crate paths, and internal issue IDs. The original
patch's cleanText()/isJargon() pass correctly scrubbed those out of
the prose parameter/return tables, but not out of the raw JSON
Schema block each page also dumps for completeness — so every one of
the 66 pages was about to publish that narration verbatim onto the
public site (private repo name, internal crate paths, an internal
issue reference, internal source file paths). Fixed by routing the
schema dump through the same cleaning pass before serializing, and by
re-running that same pass over the committed tool-schemas.json
snapshot itself so the checked-in source carries none of it either
(confirmed idempotent — regenerating from the scrubbed snapshot
reproduces byte-identical pages). Also removed
scripts/mcp-source/openapi.json, an unreferenced leftover file that
named the private crate explicitly and leaked further internal paths;
nothing in this repo reads it.

Known gap (called out in the script's own header comment)

scripts/mcp-source/tool-schemas.json is a manually-placed
snapshot, not an automated cross-repo fetch — the schema data lives
in TrueCalc's private commercial-layer repo, so the
raw.githubusercontent.com pattern gen-docs.mjs uses for the public
truecalc/core functions.json doesn't apply here without further
work (a GitHub App/token with private-repo read access, or the source
repo publishing schema dumps as a public release asset). Until that
exists, refreshing these pages means re-copying (and re-sanitizing)
tool-schemas.json by hand and re-running npm run gen-mcp-docs.
Tracked as a follow-up per the issue's own scope note.

Verification

All run locally against this branch, not just reported:

• npm run build — passes (static export)
• npm run types:check — passes
• npm run gen-mcp-docs + git diff --exit-code -- content/docs/api/mcp — clean, no drift
• npm run test-docs — 67/67 blocks pass
• npm run lint:enrichment — passes (516 files, 644 formulas)
• Manually read a fresh sample of generated pages
  (read-get-formats, format-set-conditional-format,
  history-undo, sheet-add, file-import, chart-insert,
  format-set-borders, edit-set-cell) plus index.mdx — accurate,
  no leaked internal references, sensible fallback ("Nothing beyond
  the standard MCP success envelope" / a field's description entirely
  omitted rather than left half-jargon) when nothing was salvageable.
• Swept the full diff and all 66 generated pages for the private-repo
  patterns above (repo names, crate paths, issue refs, internal file
  paths) — none remain.

Test plan for reviewer

• Skim 3–4 generated pages under content/docs/api/mcp/ for
  accuracy against the tool's actual behavior
• Confirm CI is green
• Merge when satisfied (left unmerged per this repo's own
  never-auto-merge rule)

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