chore(nests): auto-enable NestsTrace recorder in debug builds

Hook into Amethyst.onCreate behind the existing isDebug check so
the JSONL session-trace recorder lights up the moment a debug APK
launches — no per-room toggle to find, no rebuild needed to flip
the flag, no extra step on top of the existing logcat capture
flow.

Release builds are unaffected: setRecording() is gated by
`if (isDebug)`, so the volatile flag stays false and every emit
site short-circuits at the field-load + branch.

Capture from a connected receiver phone with:

  adb logcat -c
  adb logcat -s NestsTraceJsonl:D -v raw > nest-trace.jsonl

The `-v raw` formatter strips the `D NestsTraceJsonl:` prefix so
the file is valid JSONL ready for the (planned)
TraceReplayingTransport to feed back through MoqLiteSession +
NestViewModel for headless cliff-scenario regression tests.

amethyst/src/main/java/com/vitorpamplona/amethyst/Amethyst.kt

@@ -43,6 +43,12 @@ class Amethyst : Application() {
 
         if (isDebug) {
             Logging.setup()
+            // Auto-enable the Nests session-trace recorder in debug
+            // builds so two-phone repros can be captured via
+            //   adb logcat -s NestsTraceJsonl:D -v raw > nest-trace.jsonl
+            // without rebuilding to flip a flag. Off in release.
+            com.vitorpamplona.nestsclient.trace.NestsTrace
+                .setRecording(true)
         }
 
         instance.initiate(this)