Task: 10. Add config scale range validation
Date: 2026-07-06
Status: COMPLETED

Changes:
- parser/parser.c:374-377 — if scale out of [0.25, 4.0], fprintf warning + clamp to 1.0
- parser/parser.c:378-379 — if scale > 3.0, fprintf warning about unusually large scale
- Uses fprintf(stderr, ...) matching existing parser conventions

Verification:
- make debug: compiles cleanly, zero warnings
- Warning messages follow "peachwm: config: ..." format used elsewhere in parser.c
- Post-clamp check prevents double-warning when scale clamped to 1.0