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.

prisma/schema.prisma

@@ -0,0 +1,10 @@
+// Prisma schema — models added in Phase 2
+
+generator client {
+  provider = "prisma-client-js"
+}
+
+datasource db {
+  provider = "sqlite"
+  url      = env("DATABASE_URL")
+}