Initial commit: RSS platform phase 1 skeleton with code review fixes

Features:
- FastAPI + SQLAlchemy 2.0 async + PostgreSQL/pgvector + Redis backend
- Vue 3 + TypeScript + Element Plus frontend
- JWT auth with access/refresh tokens and revocation
- Admin/member RBAC
- RSS feed CRUD and article listing
- Settings management with Fernet encryption for sensitive values
- Redis distributed lock service
- Alembic initial migration
- Docker Compose development environment

Fixes from code review:
- Fix DB session leak in dependency injection
- Restrict registration to admin only
- Add default admin password warning
- Implement JWT refresh tokens and jti blacklist
- Strengthen password policy
- Use func.count for pagination totals
- Replace NullPool with AsyncAdaptedQueuePool
- Remove init_db from lifespan to enforce alembic migrations
- Add request_id middleware and logging filter
- Fix vite.config.ts env loading
- Add frontend token refresh interceptor
- Add Vue error handler

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docker/backend.Dockerfile

@@ -0,0 +1,76 @@
+# syntax=docker/dockerfile:1
+
+# ---------- Builder stage ----------
+FROM python:3.12-slim AS builder
+
+WORKDIR /build
+
+# Install build dependencies
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    gcc \
+    libpq-dev \
+    && rm -rf /var/lib/apt/lists/*
+
+# Copy dependency file
+COPY backend/pyproject.toml ./
+
+# Install dependencies into a virtual environment
+RUN python -m venv /opt/venv
+ENV PATH="/opt/venv/bin:$PATH"
+RUN pip install --no-cache-dir --upgrade pip && \
+    pip install --no-cache-dir -e .
+
+# ---------- Development stage ----------
+FROM python:3.12-slim AS development
+
+WORKDIR /app
+
+# Create non-root user
+RUN useradd --create-home --uid 1000 app && \
+    mkdir -p /app/data && \
+    chown -R app:app /app
+
+# Install runtime dependencies
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    libpq5 \
+    curl \
+    && rm -rf /var/lib/apt/lists/*
+
+# Copy virtual environment from builder
+COPY --from=builder /opt/venv /opt/venv
+ENV PATH="/opt/venv/bin:$PATH"
+
+# Switch to non-root user
+USER app
+
+EXPOSE 8000
+
+# ---------- Production stage ----------
+FROM python:3.12-slim AS production
+
+WORKDIR /app
+
+# Create non-root user
+RUN useradd --create-home --uid 1000 app && \
+    mkdir -p /app/data && \
+    chown -R app:app /app
+
+# Install runtime dependencies
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    libpq5 \
+    curl \
+    && rm -rf /var/lib/apt/lists/*
+
+# Copy virtual environment from builder
+COPY --from=builder /opt/venv /opt/venv
+ENV PATH="/opt/venv/bin:$PATH"
+
+# Copy backend code
+COPY --chown=app:app backend/ /app/
+
+# Switch to non-root user
+USER app
+
+EXPOSE 8000
+
+CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000"]