Addresses the high- and medium-priority issues from the
review subagent's pass over Phase 1+2a+2b:

Boot transaction lifecycle (was: review #1, #15)
- applyAndEmit now closes bootTx and drains in-flight phase
  spans on STOPPING / STOPPED transitions too — not just
  STARTED / ERROR. stop()-from-STARTING transitions to
  STOPPING (rule 3 of deriveLifecycleState) and bypassed
  both terminals; destroy() forcing STOPPED-via-stopRequested
  did the same. Status mapped: STARTED→ok, ERROR→
  internal_error, STOPPING/STOPPED→cancelled.
- startBootTransaction now passes a TransactionContext
  carrying TracesSamplingDecision(true, 1.0). The previous
  TransactionOptions-only setup didn't actually force
  sampling, so with the SDK default tracesSampleRate=0.0 the
  boot transaction was dropped before reaching the wire.

SentryConfig misconfig handling (was: review #3)
- Both Kotlin and Swift readers used to crash on (DSN-set,
  environment-missing) — meant to be "fail loud" but a stale
  prebuild from before the validation was added would crash
  every cold start with no recovery. Now log loud (System.err
  on Android since android.util.Log isn't mocked on JVM
  tests; NSLog on iOS) and return null (Sentry off). Updated
  test renamed to assert "returns null, doesn't throw".

Span op/description ordering (was: review #19)
- transaction.startChild(op, description) — op is the indexed
  dashboard column. Was passing ("boot", "boot.<phase>"),
  swapped to ("boot.<phase>", human-readable description) so
  the dashboard groups by the phase taxonomy that matches
  the bench backend's boot-spans.js helper.

Plugin idempotency (was: review #7)
- Previously, dropping `props.sentry` from the plugin
  registration left stale meta-data / plist entries from a
  previous prebuild (with `expo prebuild --no-clean`). Plugin
  now passes through a no-Sentry cleanup mod that strips
  every key it owns; consumer-owned keys (e.g. io.sentry.* set
  by @sentry/react-native's plugin) are untouched.

messageerror payload truncation (was: review #8)
- src/sentry.ts now truncates the wrapped error message to
  256 chars before forwarding to captureException. The
  control-frame parser surfaces offending input verbatim,
  which can include arbitrary bytes from a corrupted frame —
  truncating keeps Sentry events small and readable.

IPC + SEND_ERROR_NATIVE breadcrumbs/events (was: review #9, #10)
- NodeJSIPC's onConnectionStateChange callback wired in the
  FGS-side controlIpc construction; emits comapeo.ipc
  breadcrumbs at info (warning on Error). Per §7.4.5.
- SEND_ERROR_NATIVE_TIMEOUT_MS firing now captures a
  level=warning event with timeout:errorNativeForward tag.
  Per §7.4.4.

Logging swallowed surprises (was: review low-priority)
- SentryFgsBridge's empty `catch (t: Throwable) {}` blocks
  now Log.w so debug builds notice swallowed bridge / SDK
  bugs.

Post-init bridge tests (was: review #6)
- New SentryFgsBridgeImplTest spins up a real Sentry hub via
  the cross-platform Sentry.init(SentryOptions) path with an
  in-memory ITransport. Covers: addBreadcrumb (no envelope on
  its own), captureException + captureMessage (envelope
  enqueued), startBootTransaction with global
  tracesSampleRate=0.0 (must still reach transport thanks
  to the TracesSamplingDecision override — regression test
  for the §15 bug above), boot span lifecycle, finishSpan
  with cancelled status, unknown level fallback to INFO.

All Sentry-related tests pass: 25 cases across
SentryConfigTest (8), SentryFgsBridgeTest (10),
SentryFgsBridgeImplTest (7).

Verified locally:
- npm run lint clean
- npx tsc --noEmit clean
- ./gradlew :comapeo-core-react-native:testDebugUnitTest
  passes
- ./gradlew :comapeo-core-react-native:compileDebugKotlin
  succeeds with sentry-android on the compile classpath