Enhanced Plugin List Visual Polish

What: Multiple UI refinements to improve the plugin installation experience

Changes:

• Title capitalization: Changed "Select Marketplace" to "Select marketplace" for consistency
• Title capitalization: Changed "Install Plugins" to "Install plugins" for consistency
• Icon change: Replaced "arrowRight" (→) with "pointerSmall" (›) for better visual hierarchy
• Selection indicator: Changed from "play" (▶) to "radioOn" (◉) for selected plugins
• Improved spacing and alignment in plugin lists

• Title changes at lines 438189/438215 (v2.0.13) vs 438265/438291 (v2.0.14)
• Icon changes visible in diff at lines showing M0.pointerSmall vs q0.arrowRight and M0.radioOn vs q0.play