chore(security): 摘除 knowledge_service 硬编码默认 DeepSeek Key（缺 env 抛明确错误/503）

- knowledge_service: 移除 os.getenv 默认值占位，改 _require_deepseek_key() 必填，缺 env 抛 DeepSeekKeyMissing
- knowledge API: generate/{daily,weekly,monthly} 缺 Key 返回 503（可观测，不再静默走模板兜底）
- finance_bot / verify_zxt_vouchers_json / bot_bridge_push: 凭据改 env 优先（CMA_BOT_KEY_* / CMA_BOT_API_KEYS / CMA_BRIDGE_TOKEN），历史共享键仅作兼容期兜底并告警
- tests: 新增 5 例回归（缺 Key 服务层抛错、API 503；有 Key 正常 200）

(cherry picked from commit 859bd8276d7c5aad4bf10ee3399b6cccc188f064)

backend/tests/test_knowledge_deepseek_key_required.py

@@ -0,0 +1,92 @@
+"""knowledge_service 硬编码默认 DeepSeek Key 清理回归（2026-10-18 P2 代码卫生）
+
+覆盖：
+1. 缺 DEEPSEEK_API_KEY → 抛 DeepSeekKeyMissing（不再拿假 Key 发请求）
+2. 有 DEEPSEEK_API_KEY → 正常走请求链路并返回内容
+3. API 层：缺 Key 时 /knowledge/generate/daily 返回 503 且错误可观测（非静默模板兜底）
+4. API 层：有 Key 时行为不变（200 + 写入摘要）
+"""
+import asyncio
+import types
+
+import pytest
+from fastapi.testclient import TestClient
+from sqlalchemy.orm import Session
+
+from app.services import knowledge_service
+from app.services.knowledge_service import DeepSeekKeyMissing
+from tests.conftest import create_test_user, get_token_for_user, auth_header
+
+
+class _FakeResp:
+    status_code = 200
+
+    def json(self):
+        return {"choices": [{"message": {"content": "测试摘要：本期无重大变化。"}}]}
+
+
+class _FakeAsyncClient:
+    def __init__(self, *a, **kw):
+        pass
+
+    async def __aenter__(self):
+        return self
+
+    async def __aexit__(self, *a):
+        return False
+
+    async def post(self, *a, **kw):
+        return _FakeResp()
+
+
+def _patch_httpx(monkeypatch):
+    """只替换 knowledge_service 模块内的 httpx 引用，不动全局模块。"""
+    monkeypatch.setattr(
+        knowledge_service, "httpx", types.SimpleNamespace(AsyncClient=_FakeAsyncClient)
+    )
+
+
+# ── 服务层 ──
+
+def test_service_raises_when_key_missing(monkeypatch):
+    monkeypatch.delenv("DEEPSEEK_API_KEY", raising=False)
+    with pytest.raises(DeepSeekKeyMissing) as ei:
+        asyncio.run(knowledge_service._call_deepseek("hello"))
+    assert "DEEPSEEK_API_KEY" in str(ei.value)
+
+
+def test_service_works_when_key_present(monkeypatch):
+    monkeypatch.setenv("DEEPSEEK_API_KEY", "sk-test-not-a-real-key")
+    _patch_httpx(monkeypatch)
+    out = asyncio.run(knowledge_service._call_deepseek("hello"))
+    assert out == "测试摘要：本期无重大变化。"
+
+
+def test_require_key_strips_blank(monkeypatch):
+    monkeypatch.setenv("DEEPSEEK_API_KEY", "   ")
+    with pytest.raises(DeepSeekKeyMissing):
+        knowledge_service._require_deepseek_key()
+
+
+# ── API 层 ──
+
+def test_api_generate_daily_returns_503_without_key(client: TestClient, db: Session, monkeypatch):
+    create_test_user(db)
+    token = get_token_for_user(client, username="testadmin")
+    monkeypatch.delenv("DEEPSEEK_API_KEY", raising=False)
+
+    r = client.post("/api/cma/knowledge/generate/daily", headers=auth_header(token))
+    assert r.status_code == 503, r.text
+    detail = r.json()["detail"]
+    assert "DEEPSEEK_API_KEY" in detail, detail
+
+
+def test_api_generate_daily_ok_with_key(client: TestClient, db: Session, monkeypatch):
+    create_test_user(db)
+    token = get_token_for_user(client, username="testadmin")
+    monkeypatch.setenv("DEEPSEEK_API_KEY", "sk-test-not-a-real-key")
+    _patch_httpx(monkeypatch)
+
+    r = client.post("/api/cma/knowledge/generate/daily", headers=auth_header(token))
+    assert r.status_code == 200, r.text
+    assert r.json()["summary"]["entity_id"] == 1