Feature/mcp registry submissions - #673

Description

Makes this repo machine-legibly the source of the StackQL MCP server, to be curation-legible on GitHub's MCP registry (github.com/mcp) now and validation-ready when its auto-ingest from the Official MCP Registry lands. Metadata, discoverability and documentation only - no engine or build behaviour changes.

Changes:

• Add a repo-root server.json - a schema-valid mirror of the live Official MCP Registry entry (io.github.stackql/stackql-mcp). Single-server MCP repos that appear on github.com/mcp (e.g. github/github-mcp-server, cloudflare/mcp-server-cloudflare, grafana/mcp-grafana) all ship one at the repo their repository.url points to; this matches that convention. Field ordering follows the canonical registry/server.template.json in stackql-mcpb-packaging.
• Add a near-top "MCP Server" section to README.md (plus a TOC entry and an MCP Registry badge): the one-line pitch, the stackql mcp --mcp.server.type=stdio invocation, copy-paste mcpServers configs for every install vector (npx @stackql/mcp-server, uvx stackql-mcp-server, Docker stackql/stackql-mcp, .mcpb bundles, stackql/setup-stackql-mcp@v1), and links to the registry entry and stackql.io docs.
• Add server.json to both paths-ignore lists (push + pull_request) in .github/workflows/build.yml so this metadata file does not trigger the ~40-minute build/test matrix. README changes are already covered by the existing **/*.md ignore.

Type of change

• Bug fix (non-breaking change to fix a bug).
• Feature (non-breaking change to add functionality).
• Breaking change.
• Other (eg: documentation change). Please explain.

Documentation and discovery metadata only. No Go code, no build pipeline, and no runtime behaviour is changed. The server.json is a discovery/validation manifest consumed by external registries, not by the engine or the build.

Issues referenced.

Evidence

Validated locally (no CI runs on this PR by design - see Variations):

• server.json parses as JSON and is deep-equal to the live Official MCP Registry server object for io.github.stackql/stackql-mcp (verified against https://registry.modelcontextprotocol.io/v0/servers?search=stackql): same name, title, description, repository.url, version 0.10.500.2, and all 7 packages (mcpb x4, oci, npm, pypi).
• .github/workflows/build.yml parses as valid YAML; both the push and pull_request paths-ignore lists now contain server.json (11 entries each).
• All new README URLs return HTTP 200: the MCP Registry badge (shields.io), the registry entry (registry.modelcontextprotocol.io/?search=stackql), stackql.io/docs, releases/latest, setup-stackql-mcp, and modelcontextprotocol.io.
• Facts mirror live sources, no drift: npm @stackql/mcp-server already carries mcpName: io.github.stackql/stackql-mcp; stackql/setup-stackql-mcp@v1 tag exists with read_only as the default mode; the stackql mcp --mcp.server.type=stdio invocation matches .vscode/mcp.json.

Checklist:

• A full round of testing has been completed, and there are no test failures as a result of these changes.
• The changes are covered with functional and/or integration robot testing.
• The changes work on all supported platforms.
• Unit tests pass locally, as per the developer guide.
• Robot tests pass locally, as per the developer guide.
• Linter passes locally, as per the developer guide.

Variations

This change set touches only README.md, server.json, and the paths-ignore config in build.yml. There is no change to any Go source, robot scenario, or build behaviour, so the engine test checklist does not apply:

• Functional/integration robot testing - not applicable; no user-visible query behaviour changed. By design these changes are excluded from the Build workflow via paths-ignore, so the build/robot/integration matrix does not run on this PR.
• Unit tests / all-platforms - not applicable; no compiled code changed.
• Linter - golangci-lint covers Go only and is unaffected. server.json was validated structurally against the live registry entry and the published server.schema.json; the workflow YAML was validated by parse and by confirming both paths-ignore lists include the new file.

Tech Debt

One minor item to flag (preference is zero, this is small and bounded):

server.json is a concrete snapshot of v0.10.500. Its package identifiers are version-pinned URLs, so the snapshot stays internally correct, but its version will lag the latest Official MCP Registry entry after future releases until re-synced. The canonical source remains stackql-mcpb-packaging/registry/server.template.json (the placeholder template substituted at publish).

Resolution options (a packaging-repo change, out of scope here):

• Preferred: have the stackql-mcpb-packaging publish job also commit the substituted server.json back to this repo on release, keeping it auto-synced.
• Otherwise: a small recurring manual bump.

If the team wants this tracked rather than accepted as-is, I can open an issue in stackql-mcpb-packaging and link it here before merge.