feat(02-04): decorate 7 test files with @pytest.mark.ac markers

- test_acceptance.py: 8 decorators (AC-1.1, AC-2.1a, AC-3.3, AC-3.4, AC-4.1, AC-4.4, AC-1.4)
- test_accuracy.py: 11 decorators (AC-1.1, AC-1.2, AC-1.3, AC-2.1a, AC-2.2, AC-4.1)
- test_processor_pipe.py: 2 decorators (AC-4.4, AC-1.4)
- test_gps_input_encoding.py: module-level pytestmark for AC-4.3 (13 tests)
- test_sitl_integration.py: 9 decorators (AC-4.3, AC-4.4, AC-NEW-2, AC-5.2, AC-3.4)
- test_mavlink.py: 5 decorators (AC-4.3, AC-5.2, AC-3.4)
- test_schemas.py: 2 class-level decorators (AC-6.3, AC-6.3)
- 14 non-deferred ACs covered; 45 tests collected under -m ac

tests/test_mavlink.py

@@ -75,6 +75,7 @@ def test_unix_to_gps_time_recent():
 # MAV-02: ESKF → GPS_INPUT field mapping
 # ---------------------------------------------------------------
 
+@pytest.mark.ac("AC-4.3")
 def test_confidence_to_fix_type():
     """MAV-02: confidence tier → fix_type mapping."""
     assert _confidence_to_fix_type(ConfidenceTier.HIGH) == 3
@@ -83,6 +84,7 @@ def test_confidence_to_fix_type():
     assert _confidence_to_fix_type(ConfidenceTier.FAILED) == 0
 
 
+@pytest.mark.ac("AC-4.3")
 def test_eskf_to_gps_input_position():
     """MAV-02: ENU position → degE7 lat/lon."""
     # 1° lat ≈ 111319.5 m; move 111319.5 m North → lat + 1°
@@ -93,6 +95,7 @@ def test_eskf_to_gps_input_position():
     assert abs(msg.lat - expected_lat) <= 10  # within 1 µ-degree tolerance
 
 
+@pytest.mark.ac("AC-4.3")
 def test_eskf_to_gps_input_lon():
     """MAV-02: East displacement → longitude shift."""
     cos_lat = math.cos(math.radians(ORIGIN.lat))
@@ -212,6 +215,8 @@ def test_consecutive_failure_counter_increments_on_low(bridge):
     assert bridge._consecutive_failures == 2
 
 
+@pytest.mark.ac("AC-5.2")
+@pytest.mark.ac("AC-3.4")
 def test_reloc_request_triggered_after_3_failures(bridge):
     """MAV-04: after 3 failures the re-localisation callback is called."""
     received: list[RelocalizationRequest] = []