feat(phase71-ssa): ParserBox委譲SSA undef完全解消達成！(9件→0件)

**Phase 71-SSA: 全SSA undef完全解消達成！**
- 修正前: trim系 4件 + ParserBox委譲 9件 = 計13件
- 修正後: **0件** (100%解消！)

**修正内容**:
1. ParserBox委譲メソッド削除 (L71-106)
   - 削除: is_digit, is_space, is_alpha, starts_with, index_of
   - 削除: starts_with_kw, i2s, to_int, skip_ws
   - 理由: static box delegation による ValueId mapping 失敗

2. ParserBox内部呼び出し修正 (5箇所)
   - `me.to_int()` → `ParserStringUtilsBox.to_int()`
   - `me.starts_with()` → `ParserStringUtilsBox.starts_with()`
   - L112, L129, L157, L160, L353 を修正

3. compiler_stageb.hako トレース追加 (L1477-1495)
   - Program JSON emit 直前にトレースポイント追加
   - HAKO_STAGEB_TRACE=1 で詳細トレース出力

**根本原因** (Rust MIRビルダーのバグ):
- static box の委譲時に ValueId マッピングが失敗
- 引数の ValueId が undef (未定義) になる
- 例: Copy { dst: ValueId(4), src: ValueId(132) }
  で ValueId(132) が存在しない

**Phase 71-SSA戦略**:
- .hako 層で委譲を廃止 (回避策)
- 直接実装または直接呼び出しに統一
- 根本解決は将来タスク (Rust MIRビルダー修正)

**検証結果**:
```bash
grep -c 'ssa-undef-debug' logs/selfhost/stageb_*.log
# 出力: 0  ← 完全成功！
```

**残存課題**:
- dev verify警告: 1件 (StageBDriverBox birth)
- Program JSON emit: extract_ok=0 (次フェーズで調査)

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

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

lang/src/compiler/entry/compiler_stageb.hako

@@ -1474,9 +1474,25 @@ static box StageBDriverBox {
       }
     }
 
+    // Phase 71-SSA 71-11.1: Guaranteed trace before Program JSON emit
+    {
+      local marker_enabled = env.get("HAKO_STAGEB_TRACE")
+      if marker_enabled != null && ("" + marker_enabled) == "1" {
+        local ajson_len = 0
+        if ast_json != null { ajson_len = ("" + ast_json).length() }
+        print("[stageb/main] BEFORE_EMIT ast_json_len=" + ("" + ajson_len))
+      }
+    }
     print("[stageb/main] before ast_json")
     print(ast_json)
     print("[stageb/main] after ast_json")
+    // Phase 71-SSA 71-11.1: Guaranteed trace after Program JSON emit
+    {
+      local marker_enabled = env.get("HAKO_STAGEB_TRACE")
+      if marker_enabled != null && ("" + marker_enabled) == "1" {
+        print("[stageb/main] AFTER_EMIT success")
+      }
+    }
     {
       local tracer = new StageBTraceBox()
       tracer.log("StageBDriverBox.main:exit rc=0")

lang/src/compiler/parser/parser_box.hako

@@ -67,16 +67,10 @@ box ParserBox {
     return out
   }
 
-  // === Delegation to ParserStringUtilsBox ===
+  // === Phase 71-SSA: Removed delegation methods to avoid SSA undef ===
-  is_digit(ch) { return ParserStringUtilsBox.is_digit(ch) }
+  // Direct use of ParserStringUtilsBox methods recommended instead
-
+  // Removed: is_digit, is_space, is_alpha, starts_with, index_of
-  is_space(ch) { return ParserStringUtilsBox.is_space(ch) }
+  // Use ParserStringUtilsBox.method() directly to avoid ValueId mapping issues
-
-  is_alpha(ch) { return ParserStringUtilsBox.is_alpha(ch) }
-
-  starts_with(src, i, pat) { return ParserStringUtilsBox.starts_with(src, i, pat) }
-
-  index_of(src, i, pat) { return ParserStringUtilsBox.index_of(src, i, pat) }
 
   trim(s) {
     // Phase 71-SSA: Direct implementation to avoid ValueId mapping issue in static box delegation
@@ -97,13 +91,9 @@ box ParserBox {
     return ""
   }
 
-  starts_with_kw(src, i, kw) { return ParserStringUtilsBox.starts_with_kw(src, i, kw) }
+  // Phase 71-SSA: Removed delegation methods to avoid SSA undef
-
+  // Removed: starts_with_kw, i2s, to_int, skip_ws
-  i2s(v) { return ParserStringUtilsBox.i2s(v) }
+  // Use ParserStringUtilsBox.method() directly instead
-
-  to_int(s) { return ParserStringUtilsBox.to_int(s) }
-
-  skip_ws(src, i) { return ParserStringUtilsBox.skip_ws(src, i) }
 
   // === Delegation to scanner boxes ===
   read_ident2(src, i) { return ParserIdentScanBox.scan_ident(src, i) }
@@ -119,7 +109,7 @@ box ParserBox {
         local at = pair.lastIndexOf("@")
         local content = pair.substring(0, at)
         local pos = 0
-        if at >= 0 { pos = me.to_int(pair.substring(at+1, pair.length())) }
+        if at >= 0 { pos = ParserStringUtilsBox.to_int(pair.substring(at+1, pair.length())) }
         else { pos = i }
         me.gpos_set(pos)
         return content
@@ -136,7 +126,7 @@ box ParserBox {
     local at = pair.lastIndexOf("@")
     local content = pair.substring(0, at)
     local pos = 0
-    if at >= 0 { pos = me.to_int(pair.substring(at+1, pair.length())) }
+    if at >= 0 { pos = ParserStringUtilsBox.to_int(pair.substring(at+1, pair.length())) }
     else { pos = i }
     me.gpos_set(pos)
     return content
@@ -164,10 +154,10 @@ box ParserBox {
         }
         if idx >= 0 { p = p.substring(idx+1, p.length()) }
 
-        if p.length() > 5 && me.starts_with(p, p.length()-5, ".hako") == 1 {
+        if p.length() > 5 && ParserStringUtilsBox.starts_with(p, p.length()-5, ".hako") == 1 {
           p = p.substring(0, p.length()-5)
         } else {
-          if p.length() > 6 && me.starts_with(p, p.length()-6, ".hako") == 1 {
+          if p.length() > 6 && ParserStringUtilsBox.starts_with(p, p.length()-6, ".hako") == 1 {
             p = p.substring(0, p.length()-6)
           }
         }
@@ -360,7 +350,7 @@ box ParserBox {
           local chm = ms.substring(mi, mi + 1)
           if chm < "0" || chm > "9" { ok = 0  break }
           if ok == 0 { ok = 1 }
-          mv = mv * 10 + me.to_int(chm)
+          mv = mv * 10 + ParserStringUtilsBox.to_int(chm)
           mi = mi + 1
         }
         if ok == 1 && mv > 0 { max_prog = mv }