feat(joinir): Phase 171-fix ConditionEnv/ConditionBinding architecture

Proper HOST↔JoinIR ValueId separation for condition variables:

- Add ConditionEnv struct (name → JoinIR-local ValueId mapping)
- Add ConditionBinding struct (HOST/JoinIR ValueId pairs)
- Modify condition_to_joinir to use ConditionEnv instead of builder.variable_map
- Update Pattern2 lowerer to build ConditionEnv and ConditionBindings
- Extend JoinInlineBoundary with condition_bindings field
- Update BoundaryInjector to inject Copy instructions for condition variables

This fixes the undefined ValueId errors where HOST ValueIds were being
used directly in JoinIR instructions. Programs now execute (RC: 0),
though loop variable exit values still need Phase 172 work.

Key invariants established:
1. JoinIR uses ONLY JoinIR-local ValueIds
2. HOST↔JoinIR bridging is ONLY through JoinInlineBoundary
3. condition_to_joinir NEVER accesses builder.variable_map

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

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

src/mir/join_ir/lowering/mod.rs

@@ -14,9 +14,12 @@
 //! - `funcscanner_append_defs.rs`: FuncScannerBox._append_defs/2 の配列結合 lowering（Phase 27.14）
 //! - `if_select.rs`: Phase 33 If/Else → Select lowering
 //! - `if_dry_runner.rs`: Phase 33-10 If lowering dry-run スキャナー（箱化版）
+//! - `bool_expr_lowerer.rs`: Phase 168 Boolean expression lowering (AST → SSA)
 
+pub mod bool_expr_lowerer; // Phase 168: Boolean expression lowering for complex conditions
 pub mod carrier_info; // Phase 196: Carrier metadata for loop lowering
 pub mod common;
+pub mod condition_to_joinir; // Phase 169: JoinIR condition lowering helper
 pub mod loop_update_analyzer; // Phase 197: Update expression analyzer for carrier semantics
 pub mod exit_args_resolver;
 pub mod funcscanner_append_defs;