minimum sizes for all model controls

[saumya-pailwan]

Summary
Previously, when the HARP window was resized horizontally, several controls would shrink below a usable width. This caused Inconsistent layout behavior across different models. The goal of this fix is to ensure a minimum size for all model control widgets so that labels, sliders, toggles, combo boxes, and text fields do not collapse or overlap when the window is resized.

Changes Introduced

1. SliderWithLabel.h
   Added getMinimumWidth() helper to compute width based on text size.
   Ensures labels never overlap the rotary slider, even when window width shrinks.

2. ComboBoxWithLabel.h
   Added minimum width enforcement using label text width and padding.

3. TitledTextBox.h
   Added minimum width calculation based on title text and baseline textbox width.

4. ControlAreaWidget.h
   Replaced hardcoded constants with dynamic minimum widths

Testing Steps
Load various models (e.g., VampNet, MegaTTS3, Stable Audio 2.0). Resize the window horizontally.

Controls no longer shrink below readable/usable size
Layout feels consistent across models
All components maintain a stable minimal-width behavior

Closes #332