test(compression): make worker-specifier and RTK TOML assertions cross-platform

[Junior-HJ]

Summary

• Two compression test files fail on Windows due to POSIX-only assertions. No production code changed — test-only portability fix.
• compression-worker-pool-jam.test.ts: compared URL.pathname to a POSIX literal (/app/onnxWorker.js). On Windows pathToFileURL resolves to /D:/app/onnxWorker.js → always failed. Now compares via pathToFileURL(path.resolve(...)).pathname.
• rtk-toml-compatibility.test.ts: asserted mode & 0o777 === 0o600 — Windows has no POSIX mode bits. Gated on process.platform !== "win32", same pattern as tests/unit/data-dir-private-perms.test.ts. Atomic install + overwrite refusal still runs everywhere.

⚠️ base-red inherited: #15306

Related Issues

• Related to fix(llmlingua): pass a URL object to new Worker() instead of a file:// string #12823 (fixed prod Worker(URL) path but left the test asserting a POSIX literal)

Validation

• Change type: other (test-only)
• Focused tests: 34/34 pass on Windows
• npm run lint (exit 0)
• Reconciled with release/v3.8.52
• No production code changed

Tests Added Or Updated

• tests/unit/compression/compression-worker-pool-jam.test.ts
• tests/unit/compression/rtk-toml-compatibility.test.ts

Coverage Notes

• No production code changed. Coverage unaffected.

Reviewer Notes

• Universal: pathname assertion is platform-agnostic; mode check skipped where mode bits don't exist. Precedent: tests/unit/data-dir-private-perms.test.ts uses { skip: !posix }.