Remove legacy hardcoded 'sum' carrier validation that was blocking
array_filter patterns with different accumulator names (e.g., 'out').
Before: Pattern3 required carrier named 'sum' to exist
After: Pattern3 uses carrier_info generically (any carrier name works)
Test results:
- phase49_joinir_array_filter_smoke: PASS ✅
- phase49_joinir_array_filter_fallback: PASS ✅
- phase49_joinir_array_filter_ab_comparison: PASS ✅
- Full suite: 909/909 PASS, 0 FAIL
Also: Archive old roadmap documentation (67k lines moved to docs/archive/)
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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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