Initial commit: A-Share Data Platform v0.1.0

Parquet + DuckDB storage with REST/WebSocket APIs for Chinese A-share
market data. Supports 9 K-line frequencies with dual backend
(East Money / Sina) and auto-fallback.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.env.example

@@ -0,0 +1,24 @@
+# A-Share Data Platform Configuration
+
+# Data directory (absolute or relative to project root)
+DATA_DIR=data
+
+# DuckDB database path
+DUCKDB_PATH=data/duckdb/ashare.db
+
+# API server
+API_HOST=0.0.0.0
+API_PORT=8000
+
+# Backfill concurrency (ThreadPoolExecutor max_workers)
+BACKFILL_WORKERS=10
+
+# AKShare retry settings
+AKSHARE_MAX_RETRIES=3
+AKSHARE_RETRY_DELAY=1.0
+
+# Real-time polling interval (seconds)
+REALTIME_POLL_INTERVAL=5
+
+# Log level: DEBUG, INFO, WARNING, ERROR
+LOG_LEVEL=INFO