Extract Magic Numbers to Named Constants

Problem: Hardcoded values scattered across codebase — timeouts (600000, 30000, 5000), polling intervals, layout values (px-[100px], bg-[#FAFAFA]). Hard to maintain and inconsistent.

Expectation: Create constants files for timeouts/polling values. Extend Tailwind theme or use CSS variables for recurring layout/color values. Replace all magic numbers with named constants.