feat(config): add Pydantic config models, tests, docs and infra notes

tests/unit/test_config_models.py

@@ -0,0 +1,49 @@
+import pytest
+
+from src.server.models.config import (
+    ConfigResponse,
+    ConfigUpdate,
+    LoggingConfig,
+    SchedulerConfig,
+    ValidationResult,
+)
+
+
+def test_scheduler_defaults_and_validation():
+    sched = SchedulerConfig()
+    assert sched.enabled is True
+    assert sched.interval_minutes == 60
+
+    with pytest.raises(ValueError):
+        SchedulerConfig(interval_minutes=0)
+
+
+def test_logging_config_defaults_and_values():
+    log = LoggingConfig()
+    assert log.level == "INFO"
+    assert log.file is None
+    assert log.backup_count == 3
+
+
+def test_config_update_apply_to():
+    base = ConfigResponse(
+        scheduler=SchedulerConfig(),
+        logging=LoggingConfig(),
+        other={"a": 1},
+    )
+
+    upd = ConfigUpdate(scheduler=SchedulerConfig(enabled=False, interval_minutes=30))
+    new = upd.apply_to(base)
+    assert new.scheduler.enabled is False
+    assert new.scheduler.interval_minutes == 30
+
+    upd2 = ConfigUpdate(other={"b": 2})
+    new2 = upd2.apply_to(base)
+    assert new2.other["a"] == 1
+    assert new2.other["b"] == 2
+
+
+def test_validation_result_model():
+    vr = ValidationResult(valid=True)
+    assert vr.valid is True
+    assert isinstance(vr.errors, list)