Implement beta8 compiler functionality gate

[brik64-admin]

Summary

• upgrades the CLI candidate to 0.1.0-beta.8
• adds a bounded source-to-source compiler subset for PCD expressions, branches, and return statements
• emits executable TypeScript, Rust, and Python programs with dynamic generated tests
• adds the beta8 compiler functionality gate and evidence report

Validation

• npm run gate:beta8:compiler-functionality
• npm test
• git diff --check

Claim boundary

This is a bounded beta8 compiler-functionality candidate. It does not claim public release readiness, formal N5 status, fixpoint, self-hosting, or Rust independence.

[carlosjperez]

Reviewed beta8 candidate gates. Approval is limited to bounded compiler functionality, adversarial coverage, and local package smoke; public release remains blocked until public-surface gates pass.

[brik64-admin]

Superseded by signed single-commit PR #64 for branch-policy compliance. No admin override used.