Feature: smart handling of windows with frame constraints

[CCMurphy-dev]

Addresses issue #235 - windows with min/max size constraints (Terminal, Calculator, video players, etc.) are now handled gracefully in BSP layouts.

Implementation:

• Detect frame constraints by comparing requested vs actual size after resize
• Store detected min_size/max_size on window struct for layout calculations
• Adjust BSP split ratios to give constrained windows enough space
• Center undersized windows within their allocated node frame
• Overlap oversized windows toward screen center (not toward edges)
• Clamp manual/mouse resizes to detected min/max constraints

Safeguards:

• Auto-rebalance triggers only once per window (on first constraint detection) - to avoid looping
• Subsequent resizes skip rebalance, preventing refresh loops
• Ratio adjustments clamped to 0.1-0.9 range to prevent extreme splits

Files changed:

• src/window.h: Added min_size, max_size, has_size_constraints fields
• src/window_manager.c: Constraint detection, positioning, and resize clamping
• src/view.c: Ratio adjustment based on detected constraints