refactor(joinir): Phase 222.5 - Modularization & Determinism

Phase 222.5-B: ConditionEnv API Unification
- Remove deprecated build_loop_param_only() (v1)
- Unify build_with_captures() to use JoinValueSpace (v2 API)
- Code reduction: -17 lines
- Tests: 5/5 PASS

Phase 222.5-C: exit_binding.rs Modularization
- Split into 4 modules following Phase 33 pattern:
  - exit_binding_validator.rs (171 lines)
  - exit_binding_constructor.rs (165 lines)
  - exit_binding_applicator.rs (163 lines)
  - exit_binding.rs orchestrator (364 lines, -71 reduction)
- Single responsibility per module
- Tests: 16/16 PASS

Phase 222.5-D: HashMap → BTreeMap for Determinism
- Convert 13 critical locations to BTreeMap:
  - exit_binding (3), carrier_info (2), pattern_pipeline (1)
  - loop_update_analyzer (2), loop_with_break/continue (2)
  - pattern4_carrier_analyzer (1), condition_env (2)
- Deterministic iteration guaranteed in JoinIR pipeline
- Inventory document: phase222-5-d-hashmap-inventory.md
- Tests: 849/856 PASS (7 pre-existing failures)
- Determinism verified: 3-run consistency test PASS

Overall Impact:
- Code quality: Single responsibility, function-based design
- Determinism: JoinIR pipeline now uses BTreeMap uniformly
- Tests: All Phase 222.5 tests passing
- Documentation: Complete inventory & implementation plan

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

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

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

@@ -15,8 +15,11 @@
 //! - ast_feature_extractor.rs: Pure function module for analyzing loop AST
 //! - High reusability for Pattern 5-6 and pattern analysis tools
 //!
-//! Phase 193-4: Exit Binding Builder
-//! - exit_binding.rs: Fully boxified exit binding generation
+//! Phase 193-4 / Phase 222.5-C: Exit Binding Builder
+//! - exit_binding.rs: Fully boxified exit binding generation (orchestrator)
+//! - exit_binding_validator.rs: CarrierInfo and ExitMeta validation
+//! - exit_binding_constructor.rs: Exit binding construction and ValueId allocation
+//! - exit_binding_applicator.rs: Boundary application logic
 //! - Eliminates hardcoded variable names and ValueId assumptions
 //! - Supports both single and multi-carrier loop patterns
 //!
@@ -43,6 +46,9 @@ pub(in crate::mir::builder) mod common_init;
 pub(in crate::mir::builder) mod condition_env_builder;
 pub(in crate::mir::builder) mod conversion_pipeline;
 pub(in crate::mir::builder) mod exit_binding;
+pub(in crate::mir::builder) mod exit_binding_validator;      // Phase 222.5-C
+pub(in crate::mir::builder) mod exit_binding_constructor;    // Phase 222.5-C
+pub(in crate::mir::builder) mod exit_binding_applicator;     // Phase 222.5-C
 pub(in crate::mir::builder) mod loop_scope_shape_builder;
 pub(in crate::mir::builder) mod pattern_pipeline;
 pub(in crate::mir::builder) mod pattern1_minimal;