CLI upload regression checks

Each mutation was applied separately to src/utils/deploy/upload-files.ts and restored afterwards.

Mutation: restart retry stream at byte 1 instead of byte 0
Existing upload unit suite: 3 passed (exit 0)
New HTTP integration tests: 3 failed (exit 1)
Failure: retry payload differs from original bytes for static files, functions, and edge functions.

Mutation: resolve instead of rejecting HTTP 400/422
Existing upload unit suite: 3 passed (exit 0)
New HTTP integration tests: 2 failed (exit 1)
Failure: promise resolved [undefined] instead of rejecting.

Mutation: allow maxRetry + 1 retries
Existing upload unit suite: 3 passed (exit 0)
New HTTP integration test: 1 failed (exit 1)
Failure: last HTTP error was Upload failure 4 instead of Upload failure 3.

Mutation: replace configured concurrency with Infinity
Existing upload unit suite: 3 passed (exit 0)
New HTTP integration test: 1 failed (exit 1)
Failure: 3 simultaneous pending requests instead of 2.

Restored source: 31 deployment tests passed across 8 files.
Typecheck, focused ESLint, and oxfmt passed.

Mutation: report upload completion when the last input finishes, while earlier input is still pending
Existing upload unit suite: 3 passed (exit 0)
Initial new concurrency test: passed incorrectly (independent reviewer reproduction).
Revised concurrency test: 1 failed (exit 1)
Failure: completion callback occurred while first upload was still pending.

Review corrections: wait for client-side response settlement before checking completion; abort and drain pending requests on test failure.
Full unit suite: CI=true npm run test:unit — 640 passed, 77 files, exit 0.