feat: add extended market, offline data reader, rewrite README

- Add ExTdxClient/AsyncExTdxClient for futures, HK stocks, etc (port 7727)
- Add offline module: read daily bars, minute bars, blocks, gbbq, financials
  from local TDX installation directory (inspired by pytdx)
- Add examples 09 (file download) and 10 (offline data reading)
- Rewrite README with comprehensive API docs and code examples
- Add TdxFileNotFoundError and TdxOfflineError exceptions

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

examples/10_offline/min_bars.py

@@ -0,0 +1,83 @@
+"""演示：从本地通达信目录读取分钟 K 线数据。
+
+支持三种文件格式：
+  - .5   文件: vipdoc/{sh,sz}/fzline/  (OHLC 为整数÷100)
+  - .lc1 文件: vipdoc/{sh,sz}/fzline/ (OHLC 为浮点数)
+  - .lc5 文件: vipdoc/{sh,sz}/fzline/ (OHLC 为浮点数)
+
+需要本地已安装通达信并下载过分钟数据。
+"""
+
+from xmtdx.offline import (
+    detect_tdx_home,
+    read_5min_bars,
+    read_lc_min_bars,
+    find_5min_bar_file,
+    find_lc1_bar_file,
+    find_lc5_bar_file,
+)
+from xmtdx import Market
+
+home = detect_tdx_home()
+if home is None:
+    print("未检测到通达信安装目录，请设置 TDX_HOME 环境变量")
+    raise SystemExit(1)
+
+"""
+# --- .5 文件 (5 分钟线) ---
+print("=" * 60)
+print("5 分钟线 (.5 文件)")
+print("=" * 60)
+
+filepath = find_5min_bar_file(Market.SH, "600000")
+bars = read_5min_bars(filepath)
+if bars:
+    print(f"共 {len(bars)} 条记录，最后 5 条:")
+    for bar in bars[-5:]:
+        print(
+            f"  {bar.year}-{bar.month:02d}-{bar.day:02d} "
+            f"{bar.hour:02d}:{bar.minute:02d}  "
+            f"开{bar.open:>7.2f} 高{bar.high:>7.2f} "
+            f"低{bar.low:>7.2f} 收{bar.close:>7.2f} 量{bar.vol:>8.0f}"
+        )
+else:
+    print("未读取到数据")
+
+# --- .lc1 文件 (1 分钟线) ---
+print(f"\n{'=' * 60}")
+print("1 分钟线 (.lc1 文件)")
+print("=" * 60)
+
+filepath = find_lc1_bar_file(Market.SH, "600000")
+bars = read_lc_min_bars(filepath)
+if bars:
+    print(f"共 {len(bars)} 条记录，最后 5 条:")
+    for bar in bars[-5:]:
+        print(
+            f"  {bar.year}-{bar.month:02d}-{bar.day:02d} "
+            f"{bar.hour:02d}:{bar.minute:02d}  "
+            f"开{bar.open:>7.2f} 高{bar.high:>7.2f} "
+            f"低{bar.low:>7.2f} 收{bar.close:>7.2f} 量{bar.vol:>8.0f}"
+        )
+else:
+    print("未读取到数据")
+"""
+
+# --- .lc5 文件 (5 分钟线) ---
+print(f"\n{'=' * 60}")
+print("5 分钟线 (.lc5 文件)")
+print("=" * 60)
+
+filepath = find_lc5_bar_file(Market.SZ, "002176")
+bars = read_lc_min_bars(filepath)
+if bars:
+    print(f"共 {len(bars)} 条记录，最后 5 条:")
+    for bar in bars[-5:]:
+        print(
+            f"  {bar.year}-{bar.month:02d}-{bar.day:02d} "
+            f"{bar.hour:02d}:{bar.minute:02d}  "
+            f"开{bar.open:>7.2f} 高{bar.high:>7.2f} "
+            f"低{bar.low:>7.2f} 收{bar.close:>7.2f} 量{bar.vol:>8.0f}"
+        )
+else:
+    print("未读取到数据")