Stabilize Rust and integration test fixtures

[ceane]

Follow-up to #60.

This follow-up fixes the remaining Rust/integration test failures after the React Router migration:

• Open a managed HackRF TX subscription in the monitor worker fixture.
• Read only the encrypted binary section before decrypting v4 NAPT files, excluding the readable trailer.
• Send a valid WebSocket upgrade-shaped request so the unauthorized endpoint test reaches authentication.

Validation:

• RUSTC_WRAPPER= cargo test — 257 unit tests and all Rust integration targets passed (with the existing ignored tests).
• npm run test:integration — 11 suites, 64 tests passed.