Motivation

• Prevent QelStyleHelper from becoming a collection of per-component state-sheet functions by providing a reusable composer for common visual states.
• Let QelTheme remain the single source of token ownership while QelStyleHelper offers generic primitives to derive QSS for any component.
• Avoid forcing each new component to add a bespoke *StateStyleSheet function; components should only map theme tokens into a reusable state set.

Description

• Replace ButtonStyle with a generic ComponentStyle and add StateStyleSet to represent the six common visual states (normal, hover, active, focus, disabled, loading).
• Add composeStateStyleSheet(const QString &baseSelector, const QString &loadingSelector, const StateStyleSet &styles, bool disableFocusOutline) to generate standard state QSS for arbitrary component selectors.
• Add buttonStateStyles(...) to map button theme tokens into a StateStyleSet and keep buttonStateStyleSheet(...) as a thin wrapper that calls the generic composer for backward compatibility.
• Update QelButton::updateButtonStyle() to use QelStyleHelper::buttonStateStyleSheet(...) for state QSS while retaining geometry/size/border-radius logic inside the component.

Testing

• Attempted to build the button target with qmake QelButton/QelButton.pro -o /tmp/QelButton.Makefile && make -f /tmp/QelButton.Makefile -j2 and the command failed because qmake is not installed in the environment (command not found).
• Performed local code inspection to verify that QelButton now delegates state stylesheet composition to the helper and that the helper provides the generic composer; no runtime artifacts were produced due to the missing qmake tool.

Codex Task