chore: initial project scaffold

Set up Mangalord with a Rust/axum backend, SvelteKit frontend, Postgres,
and Docker Compose deployment. Establishes the architecture and TDD
patterns the project will extend:

- Hexagonal-ish backend layering (domain / repo / storage / api) with
  a pluggable Storage trait (LocalStorage today, S3 as a future impl).
- Initial migration: users, mangas, chapters, bookmarks.
- Vertical slice for mangas (list, search, create, get) with
  #[sqlx::test] integration coverage and storage unit tests.
- SvelteKit frontend using Svelte 5 runes, typed API client, Vitest
  unit tests and Playwright e2e with route mocking.
- CLAUDE.md documenting layering, TDD/git/SemVer workflow rules, and
  extension points (tags, fulltext search, OCR, S3, auth).
- Project-scoped .claude/settings.json with permission allowlist for
  the toolchain (git, cargo, npm/vite, docker, psql, gh, doc fetches).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/src/app.rs

@@ -0,0 +1,36 @@
+use std::sync::Arc;
+
+use axum::Router;
+use sqlx::postgres::PgPoolOptions;
+use sqlx::PgPool;
+use tower_http::trace::TraceLayer;
+
+use crate::config::Config;
+use crate::storage::{LocalStorage, Storage};
+
+#[derive(Clone)]
+pub struct AppState {
+    pub db: PgPool,
+    pub storage: Arc<dyn Storage>,
+}
+
+pub async fn build(config: Config) -> anyhow::Result<Router> {
+    let db = PgPoolOptions::new()
+        .max_connections(10)
+        .connect(&config.database_url)
+        .await?;
+    sqlx::migrate!("./migrations").run(&db).await?;
+
+    let storage: Arc<dyn Storage> = Arc::new(LocalStorage::new(config.storage_dir.clone()));
+
+    Ok(router(AppState { db, storage }))
+}
+
+/// Build a router from a pre-assembled state. Used by integration tests
+/// so they can swap in a test DB pool and a `tempfile`-backed storage.
+pub fn router(state: AppState) -> Router {
+    Router::new()
+        .nest("/api", crate::api::routes())
+        .with_state(state)
+        .layer(TraceLayer::new_for_http())
+}