Replace row-count limits with pixel-height sizing

[wowaddonmaker]

Summary

• Results dropdown height is now controlled by pixel height instead of row count, matching how width already works
• Rescaler drag handles are clamped to screen bounds so the resize overlay can't go off-screen
• Default UI results width bumped from 300 to 350

Test plan

• Open rescaler, drag bottom handle to resize results height
• Verify resize stops at screen edge (no off-screen overflow)
• Reset to defaults, confirm new default values apply
• Test with both UI search and map search results panels