feat: bot reads JIGAIDO_BOT_TOKEN from config file

- config.py: Added _resolve_bot_token() to read from config file
- bot.py: Uses config.config.bot_token instead of env var directly
- test_config.py: Added test for config file token reading

tests/test_config.py

@@ -47,10 +47,27 @@ class TestConfigDataDir:
             assert cfg.bot_token == "test_token_123"
 
     def test_bot_token_none_when_not_set(self):
-        """Test that bot_token is None when JIGAIDO_BOT_TOKEN not set."""
+        """Test that bot_token is None when JIGAIDO_BOT_TOKEN not set and no config file."""
         with patch.dict(os.environ, {}, clear=True):
-            cfg = Config()
-            assert cfg.bot_token is None
+            with patch("pathlib.Path.exists", return_value=False):
+                cfg = Config()
+                assert cfg.bot_token is None
+
+    def test_bot_token_from_config_file(self):
+        """Test that bot_token is read from config file when env var not set."""
+        config_dir = Path.home() / ".jigaido"
+        config_file = config_dir / "config.json"
+        with patch.dict(os.environ, {}, clear=True):
+            with patch("pathlib.Path.expanduser", return_value=config_file):
+                with patch("pathlib.Path.exists", return_value=True):
+                    with patch("builtins.open", create=True) as mock_open:
+                        mock_open.return_value.__enter__ = lambda s: s
+                        mock_open.return_value.__exit__ = lambda *a: None
+                        mock_open.return_value.read = lambda: (
+                            '{"JIGAIDO_BOT_TOKEN": "config_token"}'
+                        )
+                        cfg = Config()
+                        assert cfg.bot_token == "config_token"
 
 
 class TestConfigEnsureDataDir: