Give tag badges distinct colors

[marekh19]

Current: every tag (Astro, Case Study, TypeScript...) renders in an identical gold badge — no visual differentiation.

Fix: map tags to distinct hues — reuse primary/secondary/accent + daisyUI semantic colors.

One-line class-mapping change. Biggest impact-per-effort item on the list — instantly makes the blog/tag-browsing grid more scannable and colorful.