PHLEGM v6 NES Lightweight Latch Compile Fix
2026-10-02

Fixes the Windows build failure introduced by the lightweight NES vblank renderer:
  native-support.bi: Variable not declared, CartridgePpuChrIndex

The existing pure CHR-address mapper helper is now forward-declared in PHLEGM.bas before
native-support.bi is included. No mapper logic is duplicated, and observational host-side
CHR reads continue to avoid consuming cartridge FRY transactions.
