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/api/mangas.rs

@@ -0,0 +1,59 @@
+use axum::extract::{Path, Query, State};
+use axum::routing::get;
+use axum::{Json, Router};
+use serde::Deserialize;
+use uuid::Uuid;
+
+use crate::app::AppState;
+use crate::domain::manga::{Manga, NewManga};
+use crate::error::{AppError, AppResult};
+use crate::repo;
+
+pub fn routes() -> Router<AppState> {
+    Router::new()
+        .route("/mangas", get(list).post(create))
+        .route("/mangas/:id", get(get_one))
+}
+
+#[derive(Debug, Deserialize)]
+pub struct ListParams {
+    #[serde(default)]
+    pub search: Option<String>,
+    #[serde(default = "default_limit")]
+    pub limit: i64,
+    #[serde(default)]
+    pub offset: i64,
+}
+
+fn default_limit() -> i64 {
+    50
+}
+
+async fn list(
+    State(state): State<AppState>,
+    Query(params): Query<ListParams>,
+) -> AppResult<Json<Vec<Manga>>> {
+    let q = repo::manga::ListQuery {
+        search: params.search.filter(|s| !s.trim().is_empty()),
+        limit: params.limit.clamp(1, 200),
+        offset: params.offset.max(0),
+    };
+    Ok(Json(repo::manga::list(&state.db, &q).await?))
+}
+
+async fn get_one(
+    State(state): State<AppState>,
+    Path(id): Path<Uuid>,
+) -> AppResult<Json<Manga>> {
+    Ok(Json(repo::manga::get(&state.db, id).await?))
+}
+
+async fn create(
+    State(state): State<AppState>,
+    Json(input): Json<NewManga>,
+) -> AppResult<Json<Manga>> {
+    if input.title.trim().is_empty() {
+        return Err(AppError::InvalidInput("title is required".into()));
+    }
+    Ok(Json(repo::manga::create(&state.db, input).await?))
+}