Add live-stack MCP 2026-07-28 conformance testing

[lucarlig]

What this adds

• runs the official @modelcontextprotocol/conformance@0.2.0-alpha.11 server suite for MCP 2026-07-28
• tests the real public path: official runner → nginx → dataplane → official fixture
• provisions the fixture through the real control plane and publishes its configuration through Redis
• keeps the harness self-contained under tests/conformance/
• records detailed counts in the Actions log and enforces a checked-in expected-failure baseline

Live stack

The job uses Redis, nginx, and the published latest control-plane and dataplane images. The control plane uses ephemeral SQLite, so PostgreSQL and PgBouncer are not required.

The alpha.11 runner cannot send a bearer header. Nginx therefore adds an ephemeral control-plane-issued token only when the request has no authorization header. There is no auth proxy, score calculator, or repository-owned JavaScript helper. A route probe confirms traffic reached the dataplane before conformance starts.

Current baseline

Total: 76 passed, 80 failed
Baseline check passed: all failures are expected.

The conformance output remains in the Actions log; no separate conformance artifact is uploaded. Because both ContextForge images use latest, the result measures the currently published stack rather than the pull-request build. New failures and stale expected failures both fail CI.

Additional maintenance

• bumps rmcp and rmcp-macros from 3.1.1 to the latest release, 3.1.2
• updates the Pages workflow to Node 24-compatible upload/deploy actions
• installs mdBook 0.5.3 directly without the cargo-binstall fallback warning

Validation

• hosted MCP conformance workflow
• hosted Pages build without Node 20 or mdBook fallback warnings
• all repository PR checks
• actionlint, ShellCheck, Docker Compose validation, and mdBook build/tests
• workspace formatting, Clippy, and nextest with rmcp 3.1.2