docs(claude.md): Add NYASH_JOINIR_DEBUG env var documentation (Phase 195)

Document the new JoinLoopTrace unified tracing system:
- NYASH_JOINIR_DEBUG for routing and block allocation traces
- Example output format with [trace:pattern], [trace:joinir], [trace:blocks]

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

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

CLAUDE.md

@@ -37,12 +37,20 @@ NYASH_OPTION_C_DEBUG=1 cargo test --release TEST_NAME 2>&1 | grep "Option C"
 NYASH_LOOPFORM_DEBUG=1 cargo test --release TEST_NAME 2>&1 | grep "loopform"
 
 # variable_map トレース (JoinIR PHI接続デバッグ) ⭐超重要
-NYASH_TRACE_VARMAP=1 cargo test --release TEST_NAME 2>&1 | grep "varmap"
+NYASH_TRACE_VARMAP=1 cargo test --release TEST_NAME 2>&1 | grep "\[trace:"
 # 出力例:
 #   [trace:varmap] pattern3_before_merge: sum→r123, count→r124
 #   [trace:varmap] pattern3_after_merge: (merge完了後)
 #   [trace:varmap] pattern3_exit_phi_connected: sum→r456(final)
 
+# JoinIR 詳細デバッグ（ルーティング・ブロック割り当て）⭐Phase 195
+NYASH_JOINIR_DEBUG=1 ./target/release/hakorune program.hako 2>&1 | grep "\[trace:"
+# 出力例:
+#   [trace:pattern] route: Pattern1_Minimal MATCHED
+#   [trace:joinir] pattern1: 3 functions, 13 blocks
+#   [trace:blocks] allocator: Block remap: join_func_0:BasicBlockId(0) → BasicBlockId(4)
+#   [trace:routing] router: function 'main' - try_cf_loop_joinir called
+
 # 完全MIRダンプ（テスト時）
 NYASH_MIR_TEST_DUMP=1 cargo test --release TEST_NAME 2>&1 > /tmp/mir_dump.log