feat(joinir): Phase 191 body-local init integration into Pattern2

- Integrated LoopBodyLocalInitLowerer into Pattern2 lowering
- Fixed ValueId double-allocation issue (delegate to InitLowerer)
- Added body_ast parameter to lower_loop_with_break_minimal()
- Fixed json_program_loop.rs test for body-local scope
- New test: phase191_body_local_atoi.hako (expected: 123)

Supported init expressions:
- Integer literals, variable references, binary operations

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

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

src/mir/builder/control_flow/joinir/patterns/pattern2_with_break.rs

@@ -154,16 +154,13 @@ impl MirBuilder {
             id
         };
 
-        // Phase 185-2: Collect body-local variables with safe ValueId allocation
+        // Phase 191: Create empty body-local environment
+        // LoopBodyLocalInitLowerer will populate it during init lowering
         use crate::mir::join_ir::lowering::loop_body_local_env::LoopBodyLocalEnv;
-        let body_locals = collect_body_local_variables(_body, &mut alloc_body_local_value);
-        let body_local_env = LoopBodyLocalEnv::from_locals(body_locals);
+        let mut body_local_env = LoopBodyLocalEnv::new();
 
-        eprintln!("[pattern2/body-local] Phase 185-2: Collected {} body-local variables (offset={})",
-            body_local_env.len(), body_local_start_offset);
-        for (name, vid) in body_local_env.iter() {
-            eprintln!("  {} → {:?}", name, vid);
-        }
+        eprintln!("[pattern2/body-local] Phase 191: Created empty body-local environment (offset={})",
+            body_local_start_offset);
 
         // Create allocator for other JoinIR-local ValueIds (Trim pattern, etc.)
         // Continues from where body_local_counter left off
@@ -307,7 +304,8 @@ impl MirBuilder {
             &env,
             &carrier_info,
             &carrier_updates,
-            Some(&body_local_env),  // Phase 185-2: Pass body-local environment
+            _body,  // Phase 191: Pass body AST for init lowering
+            Some(&mut body_local_env),  // Phase 191: Pass mutable body-local environment
         ) {
             Ok((module, meta)) => (module, meta),
             Err(e) => {

src/mir/join_ir/lowering/loop_with_break_minimal.rs

@@ -129,7 +129,8 @@ use std::collections::HashMap;
 /// * `break_condition` - AST node for the break condition (e.g., `i >= 2`) - Phase 170-B
 /// * `carrier_info` - Phase 176-3: Carrier metadata for dynamic multi-carrier support
 /// * `carrier_updates` - Phase 176-3: Update expressions for each carrier variable
-/// * `body_local_env` - Phase 185-2: Optional body-local variable environment for update expressions
+/// * `body_ast` - Phase 191: Loop body AST for body-local init lowering
+/// * `body_local_env` - Phase 185-2: Optional mutable body-local variable environment for init expressions
 pub(crate) fn lower_loop_with_break_minimal(
     _scope: LoopScopeShape,
     condition: &ASTNode,
@@ -137,7 +138,8 @@ pub(crate) fn lower_loop_with_break_minimal(
     env: &ConditionEnv,
     carrier_info: &CarrierInfo,
     carrier_updates: &HashMap<String, UpdateExpr>,
-    body_local_env: Option<&LoopBodyLocalEnv>,
+    body_ast: &[ASTNode],
+    mut body_local_env: Option<&mut LoopBodyLocalEnv>,
 ) -> Result<(JoinModule, JoinFragmentMeta), String> {
     // Phase 170-D-impl-3: Validate that conditions only use supported variable scopes
     // LoopConditionScopeBox checks that loop conditions don't reference loop-body-local variables
@@ -308,6 +310,29 @@ pub(crate) fn lower_loop_with_break_minimal(
         cond: Some(break_cond_value),  // Phase 170-B: Use lowered condition
     });
 
+    // ------------------------------------------------------------------
+    // Phase 191: Body-Local Variable Initialization
+    // ------------------------------------------------------------------
+    // Lower body-local variable initialization expressions to JoinIR
+    // This must happen BEFORE carrier updates since carrier updates may reference body-locals
+    if let Some(ref mut body_env) = body_local_env {
+        use crate::mir::join_ir::lowering::loop_body_local_init::LoopBodyLocalInitLowerer;
+
+        // Create a mutable reference to the instruction buffer
+        let mut init_lowerer = LoopBodyLocalInitLowerer::new(
+            env,
+            &mut loop_step_func.body,
+            Box::new(&mut alloc_value),
+        );
+
+        init_lowerer.lower_inits_for_loop(body_ast, body_env)?;
+
+        eprintln!(
+            "[joinir/pattern2] Phase 191: Lowered {} body-local init expressions",
+            body_env.len()
+        );
+    }
+
     // ------------------------------------------------------------------
     // Loop Body: Compute updated values for all carriers
     // ------------------------------------------------------------------
@@ -326,7 +351,7 @@ pub(crate) fn lower_loop_with_break_minimal(
         })?;
 
         // Phase 185-2: Emit carrier update with body-local support
-        let updated_value = if let Some(body_env) = body_local_env {
+        let updated_value = if let Some(ref body_env) = body_local_env {
             // Use UpdateEnv for body-local variable resolution
             let update_env = UpdateEnv::new(env, body_env);
             emit_carrier_update_with_env(