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/Dockerfile

@@ -0,0 +1,27 @@
+# Multi-stage build for the Rust backend.
+FROM rust:1-slim AS builder
+WORKDIR /app
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends pkg-config libssl-dev ca-certificates \
+ && rm -rf /var/lib/apt/lists/*
+
+# Cache deps separately from sources.
+COPY Cargo.toml ./
+RUN mkdir src && echo "fn main() {}" > src/main.rs && echo "" > src/lib.rs \
+ && cargo build --release \
+ && rm -rf src
+
+COPY src ./src
+COPY migrations ./migrations
+RUN touch src/main.rs src/lib.rs && cargo build --release
+
+FROM debian:bookworm-slim
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends ca-certificates \
+ && rm -rf /var/lib/apt/lists/*
+WORKDIR /app
+COPY --from=builder /app/target/release/mangalord /usr/local/bin/mangalord
+COPY --from=builder /app/migrations /app/migrations
+ENV STORAGE_DIR=/var/lib/mangalord/storage
+EXPOSE 8080
+CMD ["mangalord"]