feat(joinir): Phase 213-2 Step 2-2 & 2-3 Data structure extensions

Extended PatternPipelineContext and CarrierUpdateInfo for Pattern 3 AST-based generalization.

Changes:
1. PatternPipelineContext:
   - Added loop_condition: Option<ASTNode>
   - Added loop_body: Option<Vec<ASTNode>>
   - Added loop_update_summary: Option<LoopUpdateSummary>
   - Updated build_pattern_context() for Pattern 3

2. CarrierUpdateInfo:
   - Added then_expr: Option<ASTNode>
   - Added else_expr: Option<ASTNode>
   - Updated analyze_loop_updates() with None defaults

Status: Phase 213-2 Steps 2-2 & 2-3 complete
Next: Create Pattern3IfAnalyzer to extract if statement and populate update summary

src/llvm_py/README.md

@@ -50,7 +50,7 @@ llvm_py/
 python src/llvm_py/llvm_builder.py input.mir.json -o output.o
 
 # 環境変数で切り替え（将来）
-NYASH_LLVM_USE_HARNESS=1 ./target/release/nyash program.hako
+NYASH_LLVM_USE_HARNESS=1 ./target/release/hakorune program.hako
 ```
 
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