Task: 1. Add current_scale fields to Client and LayerSurface structs
Date: 2026-07-06
Status: COMPLETED

Changes:
- include/client.h:49 — float current_scale; added to Client struct (HOT section, after corner_radius)
- include/client.h:100 — float current_scale; added to LayerSurface struct (HOT section, after mapped)

Verification:
- make debug: compiles cleanly, zero warnings
- Build artifacts confirm zero-init via ecalloc (no changes needed to allocation sites)

Evidence:
- grep 'current_scale' include/client.h → 2 matches (Client + LayerSurface)