Summary

• Canonicalize underglow keycodes (0x7820-0x782A) to UG_* in keyInfoList: label ("UG Toggle" etc.), name.long/short ("UG_TOGG" etc.), and keywords include both new UG_* and legacy RGB_* lowercase aliases for search
• Workbench keymap.c generator emits UG_* names via codeToName, and injects a RGB/UG compatibility shim (`#if !defined(UG_TOGG) && defined(RGB_TOG)` ... `#define UG_* RGB_*` ... `#endif`) so builds succeed on both modern and older QMK
• Shim stripping anchors on the `#if` signature rather than marker comments, so legacy unmarked shims, duplicated shims, and blank-line accumulation are all normalized to a single canonical block on regenerate
• QmkKeycodeMapper: UG_ALIASES inverted and renamed to LEGACY_UG_ALIASES (legacy → canonical direction), and the CODE_TO_UG_NAME override plus the UG_ branch in codeToName are removed since keyInfoList.name.long now returns UG_* naturally

Test plan

• Build keymap.c with UG_* keycodes on modern QMK that lacks legacy RGB_* macros
• Build keymap.c with UG_* keycodes on older QMK where RGB_* is defined (shim becomes a no-op)
• Import a keymap.c whose body uses legacy RGB_TOG, edit another key in the visual editor, and confirm a single canonical shim appears and the body keycodes emit UG_*
• Import a keymap.c that already contains a hand-written unmarked `#if !defined(UG_TOGG) && defined(RGB_TOG)` shim and confirm it is replaced by the canonical shim (no duplication)
• Visual editor keytop shows "UG Toggle" / "UG Mode +" etc. when the source uses UG_*
• Autocomplete popup finds the keycode when the user types "ug", "UG_TOGG", "rgb", or "rgb_tog"
• Configure domain still lets users pick these keycodes and shows the new labels