fix(joinir): Phase 241-EX - Remove hardcoded 'sum' check from Pattern3

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/)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/archive/proposals/nyash.link/universal-api-integration.md

@@ -0,0 +1,6 @@
+# nyash.link: universal API integration
+
+Status: Historical
+
+(内容は `docs/development/proposals/nyash.link/universal-api-integration.md` から移動)
+