feat(phi): Phase 69-2 Remove inspector argument from merge_exit_with_classification

Remove LocalScopeInspectorBox parameter from merge_exit_with_classification:
- Inspector is now constructed internally from exit_snapshots and header_vals
- Simplifies call sites (loopform_builder.rs, json_v0_bridge/loop_.rs)
- Removes 35+ lines of external inspector setup code
- Tests adjusted to match new signature (3 tests PASS)

This is a step toward Phase 69-3 (complete Trio deletion) where
LocalScopeInspectorBox will be fully removed.

Technical changes:
- loop_snapshot_merge.rs: Build inspector from exit_snapshots internally
- loopform_builder.rs: Remove inspector argument from build_exit_phis
- json_v0_bridge/loop_.rs: Remove inspector creation and argument

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

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

src/runner/json_v0_bridge/lowering/loop_.rs

@@ -416,15 +416,8 @@ pub(super) fn lower_loop_stmt(
     )?;
 
     // 8) exit PHI（header fallthrough + break スナップショット）
-    // Option C: Create inspector (build_exit_phis will populate it)
-    use crate::mir::phi_core::local_scope_inspector::LocalScopeInspectorBox;
-    let mut inspector = LocalScopeInspectorBox::new();
-
-    // build_exit_phis() now handles all inspector setup internally:
-    // - Records pinned/carrier definitions in header
-    // - Records filtered exit snapshots
-    // - Records header snapshot if it's an exit predecessor
-    loopform.build_exit_phis(&mut ops, exit_bb, cend, &exit_snaps, &mut inspector)?;
+    // Phase 69-2: inspector 引数削除（merge_exit_with_classification 内部で構築）
+    loopform.build_exit_phis(&mut ops, exit_bb, cend, &exit_snaps)?;
 
     Ok(exit_bb)
 }