fix: clean up pending_clusters_ when fault cleared before min_count

[eclipse0922]

Summary

• Fix phantom references in pending_clusters_ when a fault is cleared before the cluster reaches min_count
• Remove cleared fault code from pending cluster's fault_codes list
• Reassign representative based on rule policy (FIRST/MOST_RECENT/HIGHEST_SEVERITY) if the cleared fault was the representative
• Remove the pending cluster entirely when all its faults are cleared

Test plan

• ClearFaultRemovesFromPendingCluster — clearing one fault from pending cluster prevents premature activation
• ClearRepresentativeReassignsPendingCluster — representative is reassigned after clear
• ClearAllFaultsRemovesPendingCluster — clearing all faults removes the pending cluster
• All 24 correlation engine tests pass (21 existing + 3 new)
• clang-format and ament_copyright pass

Closes #127

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR fixes issue #127 by properly cleaning up pending_clusters_ when a fault is cleared before its cluster reaches min_count. The fix ensures that cleared fault codes are removed from pending clusters, representatives are reassigned when necessary, and empty pending clusters are removed entirely.

Changes:

• Enhanced process_clear() to iterate through pending_clusters_ and remove cleared faults from their respective clusters
• Implemented representative reassignment logic when the cleared fault was the cluster representative, supporting FIRST, MOST_RECENT, and HIGHEST_SEVERITY policies
• Added logic to remove pending clusters entirely when all their faults are cleared
• Added three comprehensive tests covering partial clears, representative reassignment, and complete cluster removal

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/ros2_medkit_fault_manager/src/correlation/correlation_engine.cpp	Implements cleanup logic in process_clear() to remove cleared faults from pending clusters, reassign representatives, and remove empty clusters (lines 142-179)
src/ros2_medkit_fault_manager/test/test_correlation_engine.cpp	Adds three tests: ClearFaultRemovesFromPendingCluster, ClearRepresentativeReassignsPendingCluster, and ClearAllFaultsRemovesPendingCluster to verify the fix

[mfaferek93]

LGTM!