Release 5.0.8: full-window generator rewards and security updates

[dylanuys]

Summary

• Fix generator rewards to count all eligible outcomes in the full 24-hour window, removing the global 1,000-outcome cap that could exclude older verified work. Preserve modality qualification, pass-rate calculations, and no_answer exclusion (Fix generator rewards truncated by global 1,000-outcome cap #462).
• Pin tested security updates for GitPython, Pillow, aiohttp, cryptography, FastAPI, and Starlette, with matching uv.lock metadata (Patch critical and high Dependabot alerts #461).
• Bump VERSION and gas.__version__ to 5.0.8 for validator auto-updates. Preserve main's uniform-random challenge sampling.

Validation

• Combined release suite: 212 tests passed; CI-selected Ruff checks and lockfile consistency check passed.
• Callback startup, signed upload/staging, authentication rejection, and duplicate-retry smoke tests passed with the pinned dependency versions.