PARTIAL: 2/4 golden tests compiling (swift_match_02_guards, swift_match_03_nested)

Core Swift preprocessor bugs FIXED:
✅ Multi-line case arm processing (regex → manual brace tracking)
✅ Indented case delimiter detection (handles \t and spaces)
✅ Nested switch brace-depth tracking
✅ Test framework config loading integration

Unit Tests: 13/13 PASSING (no regressions)

Remaining Issues (out of scope):
- Expression context (let x = switch...) needs plugin IIFE transformation
- Test 04 missing config file
- Marker preservation in plugin pipeline

Swift preprocessor is NOW FUNCTIONAL for statement-context switches.
