fix: complete LVGL 9.x migration for simulator

[al-munazzim]

Summary

• Complete LVGL 9.x API migration for simulator and core GUI components
• Updates event callbacks, style API, alignment methods, flag constants, and font references across 12 source files
• The scanner fix and additional python/lvgl fixes were already present in micropython-upgrade; this PR adds the remaining simulator migration changes

Changes

• Event callbacks: (obj, event) -> (event) with event.get_code()
• add_event_cb requires (callback, filter, user_data) signature
• lv.btn -> lv.button, lv.page -> lv.obj
• Style API: removed style_copy, use init() + set_*()
• Flags: OBJ_FLAG -> obj.FLAG, clear_flag -> remove_flag
• Alignment: align() -> align_to(), removed IN_ prefix
• Label: LONG.BREAK -> LONG_MODE.WRAP
• Fonts: roboto -> montserrat

Test plan

• Verify simulator builds and runs with LVGL 9.x
• Test QR scanner settings screen (HostSettings)
• Test device settings screen (DevSettings)
• Verify keyboard, mnemonic, modal, and transaction screens render correctly

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