feat(mvp): phase 1 - project scaffolding & tooling

Initialize SvelteKit project with Svelte 5, TypeScript strict, Tailwind CSS v4,
shadcn-svelte, Prisma + SQLite, Vitest, ESLint, Prettier. Add Docker multi-stage
build, docker-compose, and Gitea Actions CI pipeline.

src/routes/+page.svelte

@@ -0,0 +1,11 @@
+<script lang="ts">
+	// Placeholder — replaced in Phase 5 with the board layout
+</script>
+
+<svelte:head>
+	<title>Web App Launcher</title>
+</svelte:head>
+
+<main class="flex min-h-screen items-center justify-center bg-background text-foreground">
+	<h1 class="text-4xl font-bold">Web App Launcher</h1>
+</main>