…to prevent memory leak

  The IdentityTracker singleton never deleted entries from its internal
  maps (_currentDirectiveId, _currentDirectivePosition, isComponent) for
  destroyed directives. This caused the maps to grow monotonically for
  the entire DevTools session, retaining references to destroyed component
  instances and preventing garbage collection.

  The cleanup was intentionally commented out because the profiler needs
  to resolve IDs and positions of removed components during recording.

  Introduce `setProfilingActive()` to gate cleanup: when profiling is
  inactive, removed entries are deleted immediately during `index()`.
  When profiling is active, removals are deferred into a `_pendingRemovals`
  set and flushed once profiling stops via `capture.ts` start/stop calls.