test: Phase 3 添加 smoke test、CI 与 run-daily 去重锁

离线 mock 测试 generate 产出，GitHub Actions 跑 pytest，30 分钟内重复调度自动 skip。

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/conftest.py

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+from __future__ import annotations
+
+import json
+from datetime import datetime, timedelta, timezone
+from pathlib import Path
+
+import pytest
+
+FIXTURES = Path(__file__).parent / "fixtures"
+
+
+@pytest.fixture
+def skills_feed() -> dict:
+    return json.loads((FIXTURES / "skills-feed.json").read_text(encoding="utf-8"))
+
+
+@pytest.fixture
+def fixed_cst():
+    return datetime(2026, 7, 3, 9, 30, tzinfo=timezone(timedelta(hours=8)))
+
+
+@pytest.fixture
+def isolated_output(tmp_path, monkeypatch):
+    import daily.config as config
+    import daily.report_data as report_data
+
+    out = tmp_path / "output"
+    cache = tmp_path / "cache"
+    logs = tmp_path / "logs"
+    out.mkdir()
+    cache.mkdir()
+    logs.mkdir()
+    monkeypatch.setattr(config, "OUTPUT_DIR", out)
+    monkeypatch.setattr(report_data, "OUTPUT_DIR", out)
+    monkeypatch.setattr(config, "CACHE_DIR", cache)
+    monkeypatch.setattr(config, "LOG_DIR", logs)
+    monkeypatch.setattr(config, "SNAPSHOT_FILE", cache / "last-report.json")
+    return out
+
+
+@pytest.fixture
+def offline_generate_env(monkeypatch):
+    monkeypatch.setenv("DAILY_AI_NEWS", "0")
+    monkeypatch.setenv("DAILY_CN_AI_NEWS", "0")
+    monkeypatch.setenv("DAILY_ZH_DESC", "0")
+    monkeypatch.setenv("SKILLS_BOARD_SOURCE", "feed")
+    monkeypatch.setenv("DAILY_REPORT_MODE", "classic")
+    monkeypatch.setenv("DAILY_CURSOR_EDITOR", "0")
+    monkeypatch.setenv("DAILY_TRENDING_LIMIT", "10")
+    monkeypatch.setenv("DAILY_HOT_LIMIT", "10")