[ci] Honor CONFLICTS_WITH when grouping component tests

The test-grouping pipeline merged components that share a bus signature
into a single config without checking CONFLICTS_WITH. When
bme68x_bsec2 declared CONFLICTS_WITH=["bme680_bsec"] (and vice versa),
the merged YAML containing both failed validation.

Statically parse AUTO_LOAD and CONFLICTS_WITH from every component
__init__.py, propagate conflicts through AUTO_LOAD, and split any
group that contains a conflicting pair into separate builds.

script/test_build_components.py

@@ -37,6 +37,7 @@ from script.analyze_component_buses import (
     create_grouping_signature,
     is_platform_component,
     merge_compatible_bus_groups,
+    split_conflicting_groups,
     uses_local_file_references,
 )
 from script.helpers import get_component_test_files
@@ -675,6 +676,13 @@ def run_grouped_component_tests(
     # as long as they don't have conflicting configurations for the same bus type
     grouped_components = merge_compatible_bus_groups(grouped_components)
 
+    # Split groups that contain components declaring CONFLICTS_WITH each other.
+    # The bus-level merge above only considers shared bus configs; components
+    # with the same bus signature (e.g. both I2C) can still be mutually
+    # incompatible (e.g. bme680_bsec vs. bme68x_bsec2_i2c which auto-loads
+    # bme68x_bsec2). Those must end up in separate builds.
+    grouped_components = split_conflicting_groups(grouped_components)
+
     # Print detailed grouping plan
     print("\nGrouping Plan:")
     print("-" * 80)