Implement ScoreMR function for merge queue priority ordering with:
- Convoy age factor (prevents starvation of old convoys)
- Priority factor (P0 beats P4)
- Retry penalty (prevents thrashing on conflict-prone MRs)
- MR age tiebreaker (FIFO within same priority)
Added fields to MR struct:
- RetryCount for conflict retry tracking
- ConvoyID and ConvoyCreatedAt for convoy linkage
Includes comprehensive unit tests and documentation.
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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
