feat: add professional financial data support via calc server

Add CALC_HOSTS, financial file list/record parsing (codec/financial.py),
new client methods (get_financial_file_list, get_financial_file,
get_financial_records) with async counterparts, and example 09 demo.

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

examples/09_file_download/report_file.py

@@ -0,0 +1,102 @@
+"""演示：通过 get_report_file 从服务器下载文件。
+
+行情服务器（KNOWN_HOSTS）当前稳定提供的文件:
+  'tdxhy.cfg'      - 行业映射配置（~149KB）
+  'block_zs.dat'   - 行业/指数板块（~330KB）
+  'block_gn.dat'   - 概念板块（~757KB）
+  'block_fg.dat'   - 风格板块（~453KB）
+
+计算服务器（CALC_HOSTS）提供专业财务数据:
+  'tdxfin/gpcw.txt'                - 文件列表
+  'tdxfin/gpcwYYYYMMDD.zip'        - 历史财报
+
+行情服务器已失效（返回空包）:
+  'base_info.zip', 'gpcw.txt'
+"""
+
+from pathlib import Path
+
+from xmtdx import CALC_HOSTS, TdxClient
+
+OUTPUT_DIR = Path(__file__).parent / "downloads"
+
+# 行情服务器可用的文件
+AVAILABLE_FILES = [
+    "tdxhy.cfg",
+    "block_zs.dat",
+    "block_gn.dat",
+    "block_fg.dat",
+]
+
+# 行情服务器已失效的文件
+PROBE_FILES = ["base_info.zip", "gpcw.txt"]
+
+# ── 1. 行情服务器文件下载 ─────────────────────────────
+
+with TdxClient.from_best_host() as c:
+    OUTPUT_DIR.mkdir(exist_ok=True)
+
+    print("=" * 50)
+    print("探测已失效文件（预期返回空包）")
+    print("=" * 50)
+    for filename in PROBE_FILES:
+        data = c.get_report_file(filename)
+        status = "空包" if len(data) == 0 else f"{len(data):,} 字节"
+        print(f"  {filename}: {status}")
+
+    print()
+    print("=" * 50)
+    print("下载可用文件")
+    print("=" * 50)
+    for filename in AVAILABLE_FILES:
+        data = c.get_report_file(filename)
+        out_path = OUTPUT_DIR / filename
+        out_path.write_bytes(data)
+        print(f"  {filename} ({len(data):,} 字节) 已保存")
+
+    print()
+    print("=" * 50)
+    print("行业板块 (block_zs.dat)")
+    print("=" * 50)
+    blocks = c.get_block_info("block_zs.dat")
+    for b in blocks[:5]:
+        print(f"  {b.name:<10} 分类={b.category}  成分={b.count}")
+    print(f"  ... 共 {len(blocks)} 个")
+
+# ── 2. 计算服务器：专业财务数据 ────────────────────────
+
+print()
+print("=" * 50)
+print("专业财务数据（计算服务器）")
+print("=" * 50)
+
+calc_host = CALC_HOSTS[0]
+with TdxClient(calc_host) as c:
+    # 获取文件列表
+    file_list = c.get_financial_file_list()
+    for fi in file_list[:5]:
+        print(f"  {fi.filename}  {fi.filesize:>12,} 字节  hash={fi.hash[:8]}...")
+    print(f"  ... 共 {len(file_list)} 个文件")
+
+    # 下载并解析最近一期有实际数据的财报
+    real_files = [f for f in file_list if f.filesize > 10000]
+    if real_files:
+        latest = real_files[0]
+        fname = f"tdxfin/{latest.filename}"
+        print(f"\n下载: {fname} ({latest.filesize:,} 字节)")
+
+        # 保存原始 .zip
+        zip_data = c.get_financial_file(fname)
+        zip_path = OUTPUT_DIR / latest.filename
+        zip_path.write_bytes(zip_data)
+        print(f"  .zip 已保存到 {zip_path}")
+
+        # 解析财报记录
+        records = c.get_financial_records(fname)
+        print(f"  解析出 {len(records)} 只股票")
+        if records:
+            for r in records[:5]:
+                print(f"    {r.market.name} {r.code}  报告期={r.report_date}  字段数={len(r.fields)}")
+            print(f"    ... 共 {len(records)} 只")
+            r = records[0]
+            print(f"  示例: {r.market.name} {r.code}, 报告期={r.report_date}, 字段数={len(r.fields)}")