feat: LLM 解耦 bot、RSS 外置与内容过滤

daily 自建 Cursor bridge；DAILY_LLM_PROVIDER 控制后端；config/feeds.yaml 与 sensitive_words 可配置。

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

tests/test_llm_client.py

@@ -0,0 +1,33 @@
+from __future__ import annotations
+
+import pytest
+
+
+def test_resolve_llm_backend_prefers_cursor_in_agent_mode(monkeypatch):
+    import daily.llm_client as llm
+
+    monkeypatch.setenv("DAILY_REPORT_MODE", "agent")
+    monkeypatch.setenv("CURSOR_API_KEY", "cursor_test")
+    monkeypatch.setenv("DAILY_LLM_API_KEY", "openai_test")
+    monkeypatch.delenv("DAILY_LLM_PROVIDER", raising=False)
+    assert llm.resolve_llm_backend() == "cursor"
+
+
+def test_resolve_llm_backend_openai_override(monkeypatch):
+    import daily.llm_client as llm
+
+    monkeypatch.setenv("DAILY_REPORT_MODE", "agent")
+    monkeypatch.setenv("DAILY_LLM_PROVIDER", "openai")
+    monkeypatch.setenv("CURSOR_API_KEY", "cursor_test")
+    monkeypatch.setenv("DAILY_LLM_API_KEY", "openai_test")
+    assert llm.resolve_llm_backend() == "openai"
+
+
+def test_resolve_llm_backend_classic_defaults_openai(monkeypatch):
+    import daily.llm_client as llm
+
+    monkeypatch.setenv("DAILY_REPORT_MODE", "classic")
+    monkeypatch.setenv("CURSOR_API_KEY", "cursor_test")
+    monkeypatch.setenv("DAILY_LLM_API_KEY", "openai_test")
+    monkeypatch.delenv("DAILY_LLM_PROVIDER", raising=False)
+    assert llm.resolve_llm_backend() == "openai"