docs(normalization): Update suffix_router comments for Phase 142 P0

- Reflect that post statements are no longer required
- Document LoopOnly pattern acceptance
- Update responsibility description

Phase 142 P0: Normalization unit changed to "statement (loop only)"

src/mir/builder/control_flow/joinir/patterns/policies/normalized_shadow_suffix_router_box.rs

@@ -1,8 +1,8 @@
-//! Phase 134 P0: Suffix router box - unified with NormalizationPlanBox
+//! Phase 142 P0: Normalized shadow loop router box
 //!
 //! ## Responsibility
 //!
-//! - Detect block suffix starting with loop(true) { ... break } + post statements
+//! - Detect loop(true) patterns at block suffix (with or without subsequent statements)
 //! - Delegate to NormalizationPlanBox for pattern detection (SSOT)
 //! - Delegate to NormalizationExecuteBox for lowering and merge
 //! - Return consumed count to skip processed statements in build_block()
@@ -13,11 +13,11 @@
 //! - Returns Ok(None): Pattern not matched, use default behavior
 //! - Returns Err(_): Internal error
 //!
-//! ## Design (Phase 134 P0)
+//! ## Design (Phase 134 P0, updated Phase 142 P0)
 //!
 //! - Uses NormalizationPlanBox for detection (no duplication)
 //! - Uses NormalizationExecuteBox for execution (shared logic)
-//! - Only handles suffix-specific logic (return statement emission)
+//! - Phase 142 P0: Accepts both LoopOnly (consumed=1) and LoopWithPost patterns
 
 use crate::ast::ASTNode;
 use crate::mir::builder::MirBuilder;
@@ -27,10 +27,11 @@ use crate::mir::builder::control_flow::normalization::{NormalizationPlanBox, Nor
 pub struct NormalizedShadowSuffixRouterBox;
 
 impl NormalizedShadowSuffixRouterBox {
-    /// Try to lower a block suffix starting with loop(true) + post statements
+    /// Try to lower a loop(true) pattern in block suffix
     ///
     /// Phase 134 P0: Unified with NormalizationPlanBox for pattern detection
     /// Phase 141 P1.5: Added prefix_variables parameter for external env inputs
+    /// Phase 142 P0: Accepts both LoopOnly and LoopWithPost patterns
     ///
     /// Returns:
     /// - Ok(Some(consumed)): Successfully processed remaining[..consumed]
@@ -60,31 +61,16 @@ impl NormalizedShadowSuffixRouterBox {
             }
         };
 
-        // Only handle suffix patterns (loop + post statements)
-        // Loop-only patterns should go through try_normalized_shadow() instead
-        match &plan.kind {
-            PlanKind::LoopOnly => {
+        // Phase 142 P0: Accept both LoopOnly and LoopWithPost
+        // Normalization unit is now "statement (loop 1個)", not "block suffix"
         if debug {
-                    trace.routing(
-                        "suffix_router",
-                        func_name,
-                        "Loop-only pattern detected, not a suffix (routing.rs should handle this)",
-                    );
-                }
-                return Ok(None);
-            }
+            let description = match &plan.kind {
+                PlanKind::LoopOnly => "Loop-only pattern".to_string(),
                 PlanKind::LoopWithPost { post_assign_count } => {
-                if debug {
-                    trace.routing(
-                        "suffix_router",
-                        func_name,
-                        &format!(
-                            "Loop+post pattern detected: {} post assigns",
-                            post_assign_count
-                        ),
-                    );
-                }
+                    format!("Loop+post pattern: {} post assigns", post_assign_count)
                 }
+            };
+            trace.routing("suffix_router", func_name, &description);
         }
 
         // Phase 134 P0: Delegate execution to NormalizationExecuteBox (SSOT)