feat(core): make popup respect config sizes

[mammothb]

Problem

scale_factor, max_width, max_height, max_width_window_percentage, and max_height_window_percentage were all silently ignored for markdown images rendered in popup mode (only_render_image_at_cursor_mode = "popup").

Fix

• renderer.lua
  • Cap ALL geometry to the image's scaled natural size
• document.lua
  • Popup window pre-computes final image size

Instead of always using screen_cols / 2 as the popup width, the popup now:

1. Computes the scaled natural width (image_width / cell_width × scale_factor)
2. Caps at half screen
3. Applies max_width, max_width_window_percentage (vs screen)
4. Derives height from aspect ratio, applies max_height, max_height_window_percentage
5. Re-adjusts aspect ratio if height was constrained

Before

Details

After

Details