[TomSoulage]

Second half of #4: the fetch-results Lambda, which uses the Treize Mondial adapter (#17) and publishes MatchFinished on a new event bus.

• The final-whistle event bus and the MatchFinished contract in src/events (D28), to be shared with notify's rule in MatchFinished bus and notify #5.
• fetch-results: validates the match key, looks the match up and publishes once it is finished. Every outcome is logged as JSON with the match id, and failures are rethrown so the invocation is retried.
• An in-house JSON logger (D29) and a cold-start check of required environment variables.
• Infra: Node.js 24 on arm64, its own role limited to its log group and events:PutEvents on the bus, and a log group with a 30-day retention.

For reviewers:

• PutEvents does not throw when an entry is rejected, it only reports it in the response. publishMatchFinished turns a rejection into an error, so a score is retried rather than lost.
• Nothing invokes the Lambda yet: the planner and the one-time schedules come in Planner and one-time schedules #6. Nothing consumes the events yet: that is MatchFinished bus and notify #5. The DLQ and alarms are DLQ and alarms #7.
• The bundled handler was run locally on the live page (not finished, not found, invalid input). The finished path against the real bus will be checked by invoking the deployed Lambda after the merge.

Closes #4.