feat(agentic-rag): add multi-provider LLM, auth, and Docker support

## Added
- Multi-provider LLM support with factory pattern (8 providers):
  * OpenAI, Z.AI, OpenCode Zen, OpenRouter, Anthropic, Google, Mistral, Azure
- Authentication system: JWT + API Key dual-mode
- Provider management API (/api/v1/providers)
- Docker containerization (Dockerfile + docker-compose.yml)
- Updated documentation in main.py

## Modified
- Documents API: added authentication
- Query API: support for provider/model selection
- RAG service: dynamic LLM provider selection
- Config: multi-provider settings

## Infrastructure
- Qdrant vector store integration
- Redis support (optional)
- Health check endpoints

🚀 Ready for production deployment

Dockerfile

@@ -0,0 +1,50 @@
+# AgenticRAG Dockerfile
+# Multi-stage build for production
+
+FROM python:3.11-slim as builder
+
+WORKDIR /app
+
+# Install system dependencies
+RUN apt-get update && apt-get install -y \
+    gcc \
+    g++ \
+    curl \
+    && rm -rf /var/lib/apt/lists/*
+
+# Install Python dependencies
+COPY requirements.txt .
+RUN pip install --no-cache-dir --user -r requirements.txt
+
+# Production stage
+FROM python:3.11-slim
+
+WORKDIR /app
+
+# Copy Python packages from builder
+COPY --from=builder /root/.local /root/.local
+
+# Make sure scripts in .local are usable
+ENV PATH=/root/.local/bin:$PATH
+
+# Copy application code
+COPY src/ ./src/
+COPY static/ ./static/
+
+# Create uploads directory
+RUN mkdir -p uploads
+
+# Environment variables
+ENV PYTHONPATH=/app/src
+ENV PYTHONDONTWRITEBYTECODE=1
+ENV PYTHONUNBUFFERED=1
+
+# Expose port
+EXPOSE 8000
+
+# Health check
+HEALTHCHECK --interval=30s --timeout=30s --start-period=5s --retries=3 \
+    CMD curl -f http://localhost:8000/api/health || exit 1
+
+# Run the application
+CMD ["uvicorn", "agentic_rag.api.main:app", "--host", "0.0.0.0", "--port", "8000"]