v1.5.1 - Theme Selector, Light & Parchment UI Polish, and Cable Shadow Refinements

Changes in v1.5.1

• Appearance & Theme Selector: Added quick theme selector dropdown in the footer with full support and persistence across Midnight CAD (Dark), CAD Blueprint (Light), and Drafting Warm (Parchment) themes.
• Homepage, Login & Signup Polish: Fixed card background colors, borders, typography contrast, and form controls across light and parchment themes.
• Enclosure & Switchgear Shadows: Refined top PG glands and RAL-7032 switchgear enclosures with theme-adaptive, light-toned shadows and luminous ambient back-glow in dark mode.
• Cable Drop Shadows: Implemented pure Gaussian blur diffusion filter with subtle physical offset and reduced cable shadow opacity by 50% across all themes for a delicate, refined look.
• Pricing Tier Cards: Fixed featured 'Professional' tier card contrast and ensured 100% solid, opaque 'Most Popular' badge.