fix: apply 4 priority reliability fixes from codex analysis
- nihlathak: verify waypoint load with template check, add grayscale fallback for layout detection, guard traverse_nodes_fixed return
- npc_manager: press_npc_btn now returns bool with threshold retry (0.85->0.78) + grayscale fallback
- town/a1,a4,a5: check press_npc_btn return and verify GoldBtnVendor before proceeding
- char/i_char: expand stash waypoint close to A1_TOWN_0, add lower-threshold retry for stash in a1/a5
- char/i_char: add _weapon_switch helper that resets _active_skill cache, fix CTA switch-back validation, fix switch_sucess typo
alex
01a0351530