feat(v1): relax fall sensitivity for low overhead cameras

Adds configurable event.require_rapid_drop (default off), require_lower_body
(default off) and horizontal_angle_threshold_degrees (default 45). With the
lenient defaults a sustained horizontal pose alone enters SUSPECT and confirms
after the confirm window, which is now the main false-positive guard; missing
knees/ankles no longer reject the pose. Thresholds flow into config_version.
End-to-end smoke confirms a lying pose; 70 tests pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

v1/tests/test_config.py

@@ -140,6 +140,20 @@ def test_public_example_config_has_no_embedded_credentials():
     assert "rtsp_url_env" in source
 
 
+def test_sensitivity_fields_default_to_lenient(tmp_path):
+    config_file = tmp_path / "config.json"
+    _write_config(
+        config_file,
+        {"id": "c", "host": "192.0.2.10", "username": "u", "password": "p"},
+    )
+
+    config = load_config(config_file)
+
+    assert config.event.require_rapid_drop is False
+    assert config.event.require_lower_body is False
+    assert config.event.horizontal_angle_threshold_degrees == 45.0
+
+
 def test_build_ffmpeg_options_variants():
     assert build_ffmpeg_options() == "rtsp_transport;tcp|stimeout;5000000|fflags;nobuffer|flags;low_delay"
     assert build_ffmpeg_options("udp", 3, False) == "rtsp_transport;udp|stimeout;3000000"