[AmazingAng]

Fix six local test failures: Workers build fixtures used URL .pathname as a filesystem path, leaving spaces encoded as %20; the empty-upload deadline fixture required an exact wall-clock lower bound despite native timer rounding.

Use fileURLToPath() for filesystem paths and exercise a source directory containing spaces, #, and % in every Workers build fixture. Measure empty-upload duration with performance.now() and allow 5ms of scheduler rounding around its 400ms lower bound. Preserve timeout-error, producer cancellation, nonempty pull-count, and prompt termination assertions. Production code is unchanged.

Validation:

• bun install --frozen-lockfile passed
• bun run typecheck passed
• bun run build passed
• npm pack --dry-run --ignore-scripts passed
• Focused Workers build and native fetch fixtures: 10 passed, 0 failed
• bun run test in a checkout with spaces in its path: 1407 passed, 0 failed

No release or live xAPI verification.