With Node.js 20 the action fails with:
```
SyntaxError: The requested module 'fs' does not provide an export named 'globSync'
at ModuleJob._instantiate (node:internal/modules/esm/module_job:213:21)
at async ModuleJob.run (node:internal/modules/esm/module_job:320:5)
at async ModuleLoader.import (node:internal/modules/esm/loader:606:24)
at async asyncRunEntryPointWithESMLoader (node:internal/modules/run_main:117:5)
```
`fs.globSync` was added in Node.js 22.
Add support for SDKs that don't yet pass all conformance tests to still
run conformance in CI without failing, by specifying a YAML baseline file
of known/expected failures.
CLI changes:
- Add --expected-failures <path> flag to both server and client commands
- Exit 0 if only expected failures occur
- Exit 1 if unexpected failures occur (regression)
- Exit 1 if an expected failure now passes (stale baseline, must update)
GitHub Action (action.yml):
- Composite action that builds from source and runs conformance tests
- SDKs reference it as: uses: modelcontextprotocol/conformance@<ref>
- Inputs: mode, url, command, expected-failures, suite, scenario, etc.
New files:
- src/expected-failures.ts: YAML loading, baseline evaluation, reporting
- src/expected-failures.test.ts: 16 unit tests
- action.yml: composite GitHub Action
Closes#99
