feat: Premium redesign — GeeksPulse developer intelligence signal platform

[Copilot]

Transforms GeeksPulse from a functional minimal dark developer feed into a premium editorial platform visually aligned with GameBeeper.gg's design quality, while preserving GeeksPulse's identity, all existing JS functionality, and SEO content.

Design tokens & atmosphere (styles.css)

• New color system: dark navy #090B11 base, lime #A3FF3F brand, cyan #24D6FF technical energy, violet #8B6CFF secondary
• Body background: 3-layer radial gradient (cyan top-center, violet top-right, lime lower-left)
• Typography: Chakra Petch for display headings, JetBrains Mono for metadata/badges, Inter body
• Card hover: cyan edge glow + 3px lift; active chips/filters: lime accent
• Category color remaps: DevOps→cyan, Open Source→lime, AI/Architecture→violet, Security→red, JS→yellow

Layout (styles.css)

• 4-column CSS grid footer (desktop → 2-col tablet → 1-col mobile)
• New .value-section with 6-card responsive grid (lime/cyan/violet variants)

Markup (index.html)

• Logo: SVG pulse waveform icon (lime trace + cyan live dot) replacing "GP" text
• Hero: new eyebrow badge, headline Stay ahead of what developers build next. with lime→cyan gradient <em>, trust row (heroFeedCount+ curated sources · No ads · No paywalls · Open source), CTAs renamed to "Explore the Feed" / "Refresh Signal"
• Feed heading: "Latest" → "Latest Developer Signal"
• Sidebar panels: "bookmarks" → "my saved signal"; "stats" → "pulse status"
• Value proposition section: 6 feature cards (No Ads, No Paywalls, Trusted Sources, Curated Not Algorithmic, Open Source, Privacy First)
• Footer: rebuilt as 4-column grid — Brand, Feed, Project, Legal
• Contribute/feedback/about copy updated to new brand language

Favicon (favicon.svg)

• Lime waveform + cyan live dot on dark navy, replacing old purple accent

All JS element IDs and dynamic hooks are preserved (statFeeds, statToday, statSources, heroFeedCount, refreshBtnHero, etc.).