feat(cloudflare-pages): add authenticated Functions builds - #39

Summary

• add opt-in Cloudflare Pages Functions compilation with pinned Wrangler 4.103.0
• bind compiler inputs to Foundation-authenticated dist and functions roots and reject conflicting generated outputs
• preserve static deployment defaults while exposing the generated TypeScript option and evidence reload contract

Verification

• provider: 167 tests passed, 94.35% coverage, Ruff, format, strict mypy, Xenon A, pip-audit
• root: 219 tests passed, 96.38% coverage, quality and audit gates
• cross-language Dagger module fixtures passed
• independent review: Ready Yes, no P0-P3 findings

No Cloudflare deployment, secret mutation, registry publication, or release action was performed.