fix(ble): retry a refused pairing scan in seconds, not minutes

[cryptskii]

Summary

Bluetooth pairing after adding a contact could take a minute or two.

Cause: in the scanner role, start_ble_discovery counted the start as successful whenever advertising started, even when the scan itself was refused. Scans get refused by Android's 5-starts-per-30 s limit, or by BleCoordinator's 6 s gap between scans. The attempt then sat in WaitingForConnection waiting on a scan that never ran. Nothing retried until the 90 s stale window passed, plus up to 30 s more for the pairing loop to look again.

Fix (bluetooth/pairing_orchestrator.rs):

• In the scanner role, a refused scan is now a failed start. After 7 s (past the 6 s scan gap), after_discovery_start → discovery_refused marks an attempt still waiting for its first connection as Failed and wakes the loop, so it starts again at once.
• stale_after_secs: an attempt waiting for its first connection goes stale after 20 s. A handshake already under way keeps 90 s.
• The pairing loop wakes every 10 s (was 30 s).
• The retry logic is host-compiled and tested. Only the one-line call from the JNI spawn is Android-only.

Testing

• pairing_orchestrator tests: 11 pass, 3 of them new
  • stale windows per state, and the loop's wake interval
  • a refused scan frees only an attempt still waiting (not one reading identity, and no session is created)
  • a started discovery leaves the attempt alone; a refused one frees it after the retry delay
• clippy -D warnings (dsm_sdk --all-targets); real_code_guard.py; ci/no_clock_and_no_json.sh
• Android-target compile: not available here (the local NDK has no sysroot). The Android-only change is the single call above.

Notes

• android_ble_bridge::tests::pairing_smoke_* fail when run on their own ("Storage base directory not set"). They fail the same way on main, a different one each run, and pass in the full suite. Not touched here.
• Code-map pins are repinned in a follow-up commit once the map and evidence run.

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https://claude.ai/code/session_01Y4wDTToHmJfkYYJvMKXt3u

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