migrate CRA to Next.js 16 + React 19 + TypeScript + Tailwind v4

- replace CRA scaffold with Next.js static export config
- add app router pages: home, homelab, archive
- add components: Nav, Footer, Hero, Skills, ProjectCard, ThemeScript
- add ThemeContext for dark mode with FOUC prevention
- add data layer: projects.ts, services.ts
- update .gitignore for Next.js (ignore .next/, out/, next-env.d.ts)
- add docs: handoff plan, homelab decisions, style reference

.gitignore

@@ -1,18 +1,21 @@
-# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
-
 # dependencies
 /node_modules
 /.pnp
 .pnp.js
 
-# testing
-/coverage
+# next.js
+/.next/
+/out/
 
 # production
 /build
 
+# testing
+/coverage
+
 # misc
 .DS_Store
+.env
 .env.local
 .env.development.local
 .env.test.local
@@ -21,3 +24,10 @@
 npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
+
+# typescript
+*.tsbuildinfo
+next-env.d.ts
+
+# claude code
+.claude/