[#109.1] Fix jumping effect on initial layout - ensure consistent sizing from startup

[thomasnemer]

Parent Issue

Part of #109 - Window resize behavior conflicts with component sizing

Problem

The initial layout differs significantly from the layout after the first window resize, creating a visible "jump" when the user first resizes the window.

Expected: Panels should appear at their intended sizes immediately on startup and maintain those sizes consistently.

Observed: Initial layout is incorrect, then "snaps" to correct layout on first resize.

Root Cause Investigation Needed

Focus on understanding when and how originalWidth and originalHeight are initialized:

• Component::setAxisResizeBehavior() - initialization timing
• Component::setBounds() - how per-axis behavior is applied initially
• Component::onParentResize() - dimension tracking on first layout

Reproduction

1. Build and run the demo app: mise demo
2. Observe the initial panel layout (note widths/heights)
3. Resize window - observe the "jump" to correct layout

Success Criteria

• Initial layout matches post-resize layout
• No visual "jumping" on first window resize
• Original dimensions correctly captured at component creation
• Test in demo app confirms fix

Related Code

• include/bombfork/prong/core/component.h
• examples/demo_app/scenes/demo_scene.h