Add Free/Pro foundation and premium marketing experience

[mergemaven11]

What changed

• introduces plan/entitlement foundations for Free, Pro, Team, and Enterprise
• keeps Free intentionally useful while creating clear upgrade paths for advanced career tooling
• updates the landing page around BragStack's own product model: Proof Entries, Impact Receipts, career analytics, review/promotion outputs, and integrations
• adds four-tier pricing with Team marked coming soon and Enterprise as contact-led
• adds a BragStack-specific multi-column product footer
• adds a richer How It Works / Career Intelligence section with illustrative charts and Pro previews
• adds lightweight CSS-only motion: staggered reveals, floating proof cards, animated demo chart bars, hover depth, CTA sheen, and subtle glow movement
• respects prefers-reduced-motion
• avoids animation libraries, video backgrounds, and heavy marketing assets

Performance intent

Motion is limited to transform/opacity-oriented CSS animations and simple pseudo-elements. No animation runtime or large media dependency is introduced, so the landing experience should remain fast while feeling substantially more premium.

Validation

Preview in Codespaces on desktop and mobile widths, verify reduced-motion behavior, run frontend lint/build, and confirm plan/entitlement responses before merging.