feat: add examples (01-08), fix index bars parsing, add ruff hook

- Add example scripts for all API categories (connection, market info,
  kline, minute, transaction, finance, block, fund flow)
- Fix GetIndexBarsCmd: index bar records have 4 extra bytes (advance/
  decline counts) that were not consumed, causing pos drift and
  corrupted dates/volumes for all records after the first
- Fix price_limits.py example (SecurityQuote has no name attr)
- Fix finance_info.py display (scientific notation -> formatted numbers)
- Add PostToolUse ruff hook (scripts/ruff_hook.py)

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

scripts/ruff_hook.py

@@ -0,0 +1,43 @@
+"""PostToolUse hook: 对 Edit/Write 修改的 .py 文件自动运行 ruff check + format。
+
+stdin 接收 JSON: {"tool_name": "Edit"|"Write", "tool_input": {"file_path": "..."}}
+"""
+
+import json
+import subprocess
+import sys
+
+
+def main():
+    try:
+        data = json.load(sys.stdin)
+    except (json.JSONDecodeError, EOFError):
+        return
+
+    file_path = data.get("tool_input", {}).get("file_path", "")
+    if not file_path.endswith(".py"):
+        return
+
+    # ruff check --fix（自动修复 lint 问题）
+    r = subprocess.run(
+        ["ruff", "check", "--fix", file_path],
+        capture_output=True,
+        text=True,
+        timeout=15,
+    )
+    if r.returncode != 0 and r.stdout.strip():
+        print(f"[ruff check] {file_path}:\n{r.stdout.strip()}")
+
+    # ruff format
+    r = subprocess.run(
+        ["ruff", "format", file_path],
+        capture_output=True,
+        text=True,
+        timeout=15,
+    )
+    if r.returncode != 0 and r.stdout.strip():
+        print(f"[ruff format] {file_path}:\n{r.stdout.strip()}")
+
+
+if __name__ == "__main__":
+    main()