feat: initial @unom/app-ui — shared app-level blocks, starting with the footer

Composite UI blocks shared across the unom/punktfunk apps, one layer up from
@unom/ui (primitives). Follows the @played/app-ui pattern: per-block subpath
exports, tsdown ESM+dts build, themed through @unom/style semantic tokens.

The ./footer block exports a presentational FooterView (link sections, socials,
tagline) with a resolveHref hook so the docs can rebase root-relative links onto
the marketing-site origin. Both the punktfunk marketing site and docs render it,
so the footer no longer drifts between hand-mirrored copies.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tsconfig.json

@@ -0,0 +1,21 @@
+{
+	"compilerOptions": {
+		"target": "ES2022",
+		"lib": ["ES2022", "DOM", "DOM.Iterable"],
+		"module": "Preserve",
+		"moduleResolution": "bundler",
+		"moduleDetection": "force",
+		"jsx": "react-jsx",
+		"allowJs": true,
+		"allowImportingTsExtensions": true,
+		"verbatimModuleSyntax": true,
+		"noEmit": true,
+		"strict": true,
+		"skipLibCheck": true,
+		"noFallthroughCasesInSwitch": true,
+		"noUncheckedIndexedAccess": true,
+		"noImplicitOverride": true
+	},
+	"include": ["src"],
+	"exclude": ["node_modules", "dist"]
+}