fix(cloudflare-pages): stage Wrangler module output

[hseshadr]

TL;DR

Wrangler 4.103 serializes a multipart upload when pages functions build --outfile is used. The provider was staging that upload body as dist/_worker.js, so Cloudflare rejected the single deployment upload.

This switches the Functions build to the official --outdir module output and stages a valid advanced-mode _worker.js/ tree.

What changed

• build Pages Functions into _worker.js/ with Wrangler --outdir
• reject multipart output, unsafe module paths, output conflicts, tampering, and unauthenticated auxiliary modules before provider transport
• authenticate auxiliary module bytes against the exact closed dist/** and functions/** inputs with content-only, bounded digest queries
• preserve _routes.json, default static deployments, one provider mutation, and the existing TypeScript API
• document the advanced-mode staging and provenance contract

Regression coverage

• pinned Wrangler 4.103 real-runtime proof of runnable, non-multipart module output
• real executable input mode normalization (0755 input to 0644 output)
• toolchain Wasm escape rejection even when Wrangler omits source provenance from the metafile
• multipart, path escape, conflict, tamper, and pre-transport rejection cases

Verification

• provider: 175 passed, 93.91% coverage
• root: 219 passed, 96.38% coverage
• strict mypy, Ruff, Xenon A, per-core branch floor, schema, and dependency audits passed
• fresh dagger develop and dagger functions passed
• Python and TypeScript generated-client module fixtures passed
• independent review: Ready Yes; no Critical or Important findings

No Cloudflare credentials were used and no provider mutation was made during verification.