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/rewrite/known.rs

@@ -40,7 +40,7 @@ pub(crate) fn try_known_rewrite(
         return None;
     }
     // Receiver must be Known (origin 由来)
-    if builder.value_origin_newbox.get(&object_value).is_none() {
+    if builder.type_ctx.value_origin_newbox.get(&object_value).is_none() {
         return None;
     }
     // Only user-defined boxes (plugin/core boxesは対象外)
@@ -54,7 +54,7 @@ pub(crate) fn try_known_rewrite(
         .ok()
         .as_deref()
         == Some("1");
-    let from_new_origin = builder.value_origin_newbox.get(&object_value).is_some();
+    let from_new_origin = builder.type_ctx.value_origin_newbox.get(&object_value).is_some();
     let arity = arg_values.len();
     let fname = crate::mir::builder::calls::function_lowering::generate_method_function_name(
         cls, method, arity,
@@ -107,7 +107,7 @@ pub(crate) fn try_known_rewrite_to_dst(
     if !rewrite_enabled() {
         return None;
     }
-    if builder.value_origin_newbox.get(&object_value).is_none() {
+    if builder.type_ctx.value_origin_newbox.get(&object_value).is_none() {
         return None;
     }
     if !builder.user_defined_boxes.contains(cls) {
@@ -119,7 +119,7 @@ pub(crate) fn try_known_rewrite_to_dst(
         .ok()
         .as_deref()
         == Some("1");
-    let from_new_origin = builder.value_origin_newbox.get(&object_value).is_some();
+    let from_new_origin = builder.type_ctx.value_origin_newbox.get(&object_value).is_some();
     let arity = arg_values.len();
     let fname = crate::mir::builder::calls::function_lowering::generate_method_function_name(
         cls, method, arity,
@@ -171,7 +171,7 @@ pub(crate) fn try_unique_suffix_rewrite(
         return None;
     }
     // Only attempt if receiver is Known (keeps behavior stable and avoids surprises)
-    if builder.value_origin_newbox.get(&object_value).is_none() {
+    if builder.type_ctx.value_origin_newbox.get(&object_value).is_none() {
         return None;
     }
     let mut cands: Vec<String> = builder.method_candidates(method, arg_values.len());
@@ -200,7 +200,7 @@ pub(crate) fn try_unique_suffix_rewrite(
     }
     builder.annotate_call_result_from_func_name(dst, &fname);
     let meta = serde_json::json!({
-        "recv_cls": builder.value_origin_newbox.get(&object_value).cloned().unwrap_or_default(),
+        "recv_cls": builder.type_ctx.value_origin_newbox.get(&object_value).cloned().unwrap_or_default(),
         "method": method,
         "arity": arity_us,
         "chosen": fname,
@@ -222,7 +222,7 @@ pub(crate) fn try_unique_suffix_rewrite_to_dst(
     if !rewrite_enabled() {
         return None;
     }
-    if builder.value_origin_newbox.get(&object_value).is_none() {
+    if builder.type_ctx.value_origin_newbox.get(&object_value).is_none() {
         return None;
     }
     let mut cands: Vec<String> = builder.method_candidates(method, arg_values.len());
@@ -255,7 +255,7 @@ pub(crate) fn try_unique_suffix_rewrite_to_dst(
     }
     builder.annotate_call_result_from_func_name(actual_dst, &fname);
     let meta = serde_json::json!({
-        "recv_cls": builder.value_origin_newbox.get(&object_value).cloned().unwrap_or_default(),
+        "recv_cls": builder.type_ctx.value_origin_newbox.get(&object_value).cloned().unwrap_or_default(),
         "method": method,
         "arity": arity_us,
         "chosen": fname,