refactor(mir): Remove TypeContext legacy fields (Phase 2-3/7)

完全移行→削除の安全順序（Option C）に従い、TypeContext の
deprecated フィールドと sync helpers を完全削除。

⚠️ 危険ゾーン: TypeFactsBox 等の同名フィールドと混同しないよう、
ファイル単位で手作業移行を実施。

## Changes
- Migrated all MirBuilder access sites to type_ctx.* (manual, 40+ files)
- Removed 3 deprecated fields (value_types, value_kinds, value_origin_newbox)
- Removed 2 sync helpers (sync_type_ctx_to_legacy, sync_legacy_to_type_ctx)
- Verified TypeFactsBox, CalleeGuardBox unchanged (no false positives)

## Tests
- cargo test --release --lib: 1029/1033 PASS
- TypeFactsBox integration: PASS (borrowed references unchanged)
- Deprecation warnings: 456 → 255 (-201, -44%)

## Safety Verification
✅ TypeFactsBox unchanged (still uses &'a BTreeMap borrowed references)
✅ CalleeGuardBox unchanged
✅ CalleeResolverBox unchanged
✅ BoxCompilationContext unchanged

Phase 2 Progress: 3/7 contexts complete (43%)
- ✅ MetadataContext
- ✅ CoreContext
- ✅ TypeContext (this commit)

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

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

src/mir/builder/emission/compare.rs

@@ -17,7 +17,7 @@ pub fn emit_to(
         b.emit_instruction(MirInstruction::Compare { dst, op, lhs, rhs })?;
     }
     // 比較結果は Bool 型（既存実装と同じ振る舞い）
-    b.value_types.insert(dst, MirType::Bool);
+    b.type_ctx.value_types.insert(dst, MirType::Bool);
     Ok(())
 }
 

src/mir/builder/emission/constant.rs

@@ -14,7 +14,7 @@ pub fn emit_integer(b: &mut MirBuilder, val: i64) -> ValueId {
         value: ConstValue::Integer(val),
     });
     // Phase 84-1: Integer constant type annotation
-    b.value_types.insert(dst, crate::mir::MirType::Integer);
+    b.type_ctx.value_types.insert(dst, crate::mir::MirType::Integer);
     dst
 }
 
@@ -26,7 +26,7 @@ pub fn emit_bool(b: &mut MirBuilder, val: bool) -> ValueId {
         value: ConstValue::Bool(val),
     });
     // Phase 84-1: Bool constant type annotation
-    b.value_types.insert(dst, crate::mir::MirType::Bool);
+    b.type_ctx.value_types.insert(dst, crate::mir::MirType::Bool);
     dst
 }
 
@@ -38,7 +38,7 @@ pub fn emit_float(b: &mut MirBuilder, val: f64) -> ValueId {
         value: ConstValue::Float(val),
     });
     // Phase 84-1: Float constant type annotation
-    b.value_types.insert(dst, crate::mir::MirType::Float);
+    b.type_ctx.value_types.insert(dst, crate::mir::MirType::Float);
     dst
 }
 
@@ -51,9 +51,9 @@ pub fn emit_string<S: Into<String>>(b: &mut MirBuilder, s: S) -> ValueId {
     });
     // 🎯 Phase 3-A: String constant type annotation
     // Ensures string constants have proper Box type for method resolution
-    b.value_types
+    b.type_ctx.value_types
         .insert(dst, crate::mir::MirType::Box("StringBox".to_string()));
-    b.value_origin_newbox.insert(dst, "StringBox".to_string());
+    b.type_ctx.value_origin_newbox.insert(dst, "StringBox".to_string());
     dst
 }
 
@@ -66,7 +66,7 @@ pub fn emit_null(b: &mut MirBuilder) -> ValueId {
     });
     // Phase 84-1: Null constant type annotation
     // Note: MirType has no Null variant, using Unknown as fallback
-    b.value_types.insert(dst, crate::mir::MirType::Unknown);
+    b.type_ctx.value_types.insert(dst, crate::mir::MirType::Unknown);
     dst
 }
 
@@ -78,6 +78,6 @@ pub fn emit_void(b: &mut MirBuilder) -> ValueId {
         value: ConstValue::Void,
     });
     // Phase 84-1: Void constant type annotation
-    b.value_types.insert(dst, crate::mir::MirType::Void);
+    b.type_ctx.value_types.insert(dst, crate::mir::MirType::Void);
     dst
 }