Improvements:
- Renamed FirstLocalThenGlobalErrorFilter to GlobalIfNoLocalErrorFilter for better clarity
- Name now clearly indicates "global if no local handler" behavior

New Features:
- Added GlobalErrorFilter that routes errors ONLY to global handler
- Returns ErrorReaction.globalHandler (not firstLocalThenGlobal)
- Useful when you want all errors to go global regardless of local listeners

Fixes:
- Removed incorrectly deprecated GlobalErrorFilter from v9.1.0
- Replaced with correct implementation

Tests:
- Added test for GlobalErrorFilter behavior
- All 38 tests passing