Refactor into modular app structure

Split monolithic files into focused modules:
- app/core: settings, logging, lifecycle
- app/signaling: websocket server, ICE parser, message models
- app/webrtc: peer session, video receiver, frame source
- app/vision: pose landmarker wrapper, model config, pose types
- app/exercises/dead_bug: detector, metrics, rules, state machine, types
- app/rendering: skeleton renderer, status overlay, window display
- app/audio: rep announcer
- app/diagnostics: perf timer, crash handler
- configs: environment-based settings
- tests: unit tests for rules, state machine, ICE parser
- run.py: entry point

tests/test_dead_bug_rules.py

@@ -0,0 +1,65 @@
+from __future__ import annotations
+
+from app.exercises.dead_bug.metrics import calculate_metrics
+from app.exercises.dead_bug.rules import detect_diagonal_extension, has_required_visibility, is_ready_position
+from app.exercises.dead_bug.state_machine import DeadBugStateMachine
+from app.exercises.dead_bug.types import DeadBugMetrics, DeadBugPhase, Point
+
+
+class TestDeadBugRules:
+    def _make_landmark(self, x=0.5, y=0.5, z=0.0, visibility=1.0):
+        return Point(x, y, z, visibility)
+
+    def _make_visible_landmarks(self):
+        return [self._make_landmark() for _ in range(33)]
+
+    def test_has_required_visibility_all_visible(self):
+        lm = self._make_visible_landmarks()
+        indices = (11, 12, 13, 14, 15, 16, 23, 24, 25, 26, 27, 28)
+        assert has_required_visibility(lm, indices, 0.45)
+
+    def test_has_required_visibility_low(self):
+        lm = self._make_visible_landmarks()
+        lm[11] = self._make_landmark(visibility=0.1)
+        indices = (11, 12, 13, 14, 15, 16, 23, 24, 25, 26, 27, 28)
+        assert not has_required_visibility(lm, indices, 0.45)
+
+    def test_detect_diagonal_extension_none(self):
+        metrics = DeadBugMetrics(
+            left_arm_extended=False, right_arm_extended=False,
+            left_leg_extended=False, right_leg_extended=False,
+            left_elbow_angle=90, right_elbow_angle=90,
+            left_knee_angle=90, right_knee_angle=90,
+            feedback=[],
+        )
+        assert detect_diagonal_extension(metrics) is None
+
+    def test_detect_diagonal_extension_left_arm_right_leg(self):
+        metrics = DeadBugMetrics(
+            left_arm_extended=True, right_arm_extended=False,
+            left_leg_extended=False, right_leg_extended=True,
+            left_elbow_angle=160, right_elbow_angle=90,
+            left_knee_angle=90, right_knee_angle=160,
+            feedback=[],
+        )
+        assert detect_diagonal_extension(metrics) == "left_arm_right_leg"
+
+    def test_is_ready_position(self):
+        metrics = DeadBugMetrics(
+            left_arm_extended=False, right_arm_extended=False,
+            left_leg_extended=False, right_leg_extended=False,
+            left_elbow_angle=90, right_elbow_angle=90,
+            left_knee_angle=100, right_knee_angle=100,
+            feedback=[],
+        )
+        assert is_ready_position(metrics)
+
+    def test_is_not_ready_legs_extended(self):
+        metrics = DeadBugMetrics(
+            left_arm_extended=False, right_arm_extended=False,
+            left_leg_extended=True, right_leg_extended=False,
+            left_elbow_angle=90, right_elbow_angle=90,
+            left_knee_angle=100, right_knee_angle=100,
+            feedback=[],
+        )
+        assert not is_ready_position(metrics)

tests/test_dead_bug_state_machine.py

@@ -0,0 +1,42 @@
+from __future__ import annotations
+
+from app.exercises.dead_bug.state_machine import DeadBugStateMachine
+from app.exercises.dead_bug.types import DeadBugMetrics, DeadBugPhase
+
+
+class TestDeadBugStateMachine:
+    def _ready_metrics(self) -> DeadBugMetrics:
+        return DeadBugMetrics(
+            left_arm_extended=False, right_arm_extended=False,
+            left_leg_extended=False, right_leg_extended=False,
+            left_elbow_angle=90, right_elbow_angle=90,
+            left_knee_angle=100, right_knee_angle=100,
+            feedback=[],
+        )
+
+    def _extended_left(self) -> DeadBugMetrics:
+        return DeadBugMetrics(
+            left_arm_extended=True, right_arm_extended=False,
+            left_leg_extended=False, right_leg_extended=True,
+            left_elbow_angle=160, right_elbow_angle=90,
+            left_knee_angle=90, right_knee_angle=160,
+            feedback=[],
+        )
+
+    def test_initial_state(self):
+        sm = DeadBugStateMachine()
+        assert sm.phase == DeadBugPhase.READY
+        assert sm.rep_count == 0
+
+    def test_no_transition_in_ready(self):
+        sm = DeadBugStateMachine()
+        result = sm.update(self._ready_metrics())
+        assert sm.phase == DeadBugPhase.READY
+        assert result.rep_count == 0
+
+    def test_confirm_extension(self):
+        sm = DeadBugStateMachine(extension_confirm_frames=2, reset_confirm_frames=2)
+        sm.update(self._extended_left())
+        assert sm.phase == DeadBugPhase.READY
+        sm.update(self._extended_left())
+        assert sm.phase == DeadBugPhase.EXTENDING

tests/test_ice_parser.py

@@ -0,0 +1,35 @@
+from __future__ import annotations
+
+from app.signaling.ice_parser import parse_ice
+
+
+class TestIceParser:
+    def test_parse_valid_ice(self):
+        data = {
+            "candidate": "1234567890 1 UDP 2130706431 192.168.1.1 12345 typ host",
+            "sdpMid": "0",
+            "sdpMLineIndex": 0,
+        }
+        cand = parse_ice(data)
+        assert cand is not None
+        assert cand.foundation == "1234567890"
+        assert cand.component == 1
+        assert cand.protocol == "udp"
+        assert cand.ip == "192.168.1.1"
+        assert cand.port == 12345
+        assert cand.type == "host"
+
+    def test_parse_invalid_ice(self):
+        assert parse_ice({"candidate": "invalid"}) is None
+
+    def test_parse_srflx(self):
+        data = {
+            "candidate": "abcdef 1 UDP 1686052607 203.0.113.1 50000 typ srflx raddr 192.168.1.1 rport 12345",
+            "sdpMid": "0",
+            "sdpMLineIndex": 0,
+        }
+        cand = parse_ice(data)
+        assert cand is not None
+        assert cand.type == "srflx"
+        assert cand.relatedAddress == "192.168.1.1"
+        assert cand.relatedPort == 12345