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

tools/ny_parser_mvp_roundtrip.sh

@@ -3,10 +3,10 @@ set -euo pipefail
 
 SCRIPT_DIR=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)
 ROOT_DIR=$(CDPATH= cd -- "$SCRIPT_DIR/.." && pwd)
-BIN="$ROOT_DIR/target/release/nyash"
+BIN="$ROOT_DIR/target/release/hakorune"
 
 if [[ ! -x "$BIN" ]]; then
-  echo "[build] nyash (release) ..." >&2
+  echo "[build] hakorune (release) ..." >&2
   cargo build --release >/dev/null
 fi