[ceane]

Summary

• Show explicit file, stale-device, and reconnect states and restore live streams after reload or device interruptions.
• Round and validate stream center frequencies as whole hertz before sending them to the backend.
• Include both waterfall snapshot commits so exported dB bounds reflect the displayed range.

Verification

• 240 focused Jest tests passed, plus the waterfall state fixture tests.
• TypeScript typecheck passed in the feature worktree.
• Rust liveness test and cargo check passed for the same Rust change.
• RTL-SDR recovery was observed in the live app after a backend hot reload.