Shift config of "known-sdks.ts" to SDK-side config file

I really like the idea of easing the options handling and execution of the conformance runner, but immediately fell into the pitfall that this requires cross repo PRs and also decouples the versioning a bit inconvenient if changes are needed.

of course the sdk map would stay in this repo, but after checkout it could check for a conformance.yaml with the relevant settings:

# modelcontextprotocol/go-sdk
# conformance.yaml
build: 'go build -o ./.conformance-server ./conformance/everything-server && go build -o ./.conformance-client ./conformance/everything-client'
client:
    command: './.conformance-client'
server:
    command: './.conformance-server -http=localhost:3000 -stateless=false'
    url: 'http://localhost:3000'
expectedFailures: 'conformance/baseline.yml'
specOverrides:
    '2026-07-28':
        server: { command: './.conformance-server -http=localhost:3000' }

WDYT?

Start by reading known-sdks.ts and the conformance runner's current options-handling path; the issue proposes moving SDK-specific settings into an SDK-side conformance.yaml while keeping the SDK map in this repository. Compare the proposed build, client, server, expectedFailures, and specOverrides fields with the current configuration, and consider how existing baseline.yml handling is affected. Done means the runner can obtain these settings from the checked-out SDK without requiring cross-repository configuration changes.