fix(ci-replay): restore replay result reports and stabilize Linux headless CI

[fbraz3]

Summary

Restores the detailed per-replay pass/fail reporting in the replay test workflow for both Linux and macOS, while keeping the stability fixes that were applied during the bugfix cycle.

Changes

.github/workflows/replay-tests.yml

• Restored per-replay reporting: Added detailed pass/fail status for each replay file in both Linux and macOS jobs.
• Replay summary table: Generates a markdown table in GITHUB_STEP_SUMMARY with columns: Replay | Result | Details.
• Result accounting: Tracks PASS and FAIL counters and outputs final summary totals.
• CI failure behavior: Job fails explicitly when at least one replay fails.
• Warning for empty replay sets: Emits warning when no replay files are found.
• Linux headless stability: Keeps SDL dummy driver configuration (SDL_VIDEODRIVER=dummy, SDL_AUDIODRIVER=dummy) for headless replay execution on runners without display devices.

docs/DEV_BLOG/2026-05-DIARY.md

• Documented the replay report restoration in the May 2026 development diary.

Validation

• Workflow diagnostics are clean after the changes.
• Ready for manual workflow execution to validate the restored reporting format.

Testing

• Manual workflow run recommended to confirm the restored reporting format works as expected on both Linux and macOS runners.