feat: Rust refactor — full backend rewrite (Phases 1-6)

Phase 1-3: Scaffold + types + auth (JWT, Argon2, API keys)
Phase 4a: Admin API (sites/accounts/tokens/downstream-keys/settings)
Phase 5: Proxy core (/v1/chat, /v1/images, /v1/models)
Phase 6: ComfyUI proxy routes migrated

- 80+ source files, all cargo check + 18 tests green
- Drop-in compatible with Node.js API surface

boosapi-rs/docker/Dockerfile

@@ -0,0 +1,18 @@
+# Build stage
+FROM rust:1.85-slim-bookworm AS builder
+WORKDIR /app
+RUN apt-get update && apt-get install -y pkg-config libssl-dev
+COPY Cargo.toml Cargo.lock ./
+RUN mkdir src && echo "fn main() {}" > src/main.rs
+RUN cargo build --release 2>/dev/null || true
+COPY . .
+RUN cargo build --release
+
+# Runtime stage
+FROM debian:bookworm-slim
+RUN apt-get update && apt-get install -y ca-certificates && rm -rf /var/lib/apt/lists/*
+WORKDIR /app
+COPY --from=builder /app/target/release/boosapi /app/
+COPY --from=builder /app/migrations /app/migrations
+EXPOSE 4000
+CMD ["/app/boosapi"]