Port OnionUI PRs #1936–#1946 (launch prep, fb transitions, GameSwitcher favorites/crash fixes, theme previews) — thanks @robcodedev

[Copilot]

Summary

Ports 11 upstream PRs from OnionUI/Onion onto the OnionPlus build, with full bug-check and build verification.

🙏 Credits: all the original work behind these PRs is by @robcodedev — a fantastic optimization and hardening effort on Onion. This PR only ports his changes onto our build, adapting them where the fork diverges (Flip support, advmenu, extended keymon, the fork's existing process_* / file_resolvePath helpers).

Ported PRs

Upstream PR	Title	Files touched
#1936	keymon: refresh system state before acting on SELECT	src/keymon/keymon.c
#1937	Fix JSON error in lt.lang (missing comma)	static/build/miyoo/app/lang/lt.lang
#1938	ThemeSwitcher: load theme previews on demand (5-slot LRU cache) + archive stat cache	src/themeSwitcher/*, themes_extract_previews.sh
#1939	GameSwitcher: Favorites toggle + crash/game-switching fixes (save-state scan thread safety, targeted RetroArch kill by PID)	src/gameSwitcher/* (new gs_favorites.h), src/common/system/lang.h, en.lang
#1940	New fbmode tool + improved framebuffer transitions and screen init	src/fbmode/* (new), Makefile, runtime.sh, change_resolution.sh, .force640Res_
#1941	Clear /tmp/.forceKillRetroarch before each launch (atomic consume)	runtime.sh
#1942	Keep ROM list positions (romwinidx.json) on the SD card	runtime.sh
#1943	Track theme icon reapply per device, not per card	runtime.sh
#1944	Cap recents at 200 when toggling hidden games	runtime.sh
#1945	Stop repatching retroarch.cfg on every launch	runtime.sh
#1946	Overlap launch preparation (background playActivity + killall, joined before emulator handoff)	runtime.sh

Adaptations vs upstream

• gs_overlay.h: kept the fork's native process_killall_signal/process_killall fallback on the no-captured-PID path, with the original waits (10×500 ms)
• installTheme.h: preserved the *count >= NUMBER_OF_THEMES bound check already present in the fork (extended with log + snprintf)
• keymon.c: inserted system_state_update() into the fork's extended SELECT handler (AXP/Flip)
• No behaviour removed: all upstream fbset fallback paths were preserved

Verification

• ✅ Host test suite: 1,414 tests / 71,400 assertions — ALL PASSED (including test_gs_popmenu, test_lang, test_list, test_process)
• ✅ Clean cross-compile (miyoomini toolchain) for gameSwitcher, themeSwitcher, keymon, fbmode — the only warning is a pre-existing strncpy one in untouched state.h
• ✅ sh -n on runtime.sh and change_resolution.sh; valid JSON for lt.lang and en.lang
• ✅ Code review: no findings; CodeQL: 0 alerts
• ⚠️ To be validated on real hardware (Mini / Mini+ / Flip): the Improve framebuffer transitions and 640x480 handling OnionUI/Onion#1940 framebuffer (mi_fb) and Overlap launch preparation OnionUI/Onion#1946 launch-timing paths, which the host suite cannot cover