wip(stage1): StringHelpers.skip_ws receiver捏造問題の応急処置

- 問題: StaticCompiler method呼び出し時にreceiver ValueIdが捏造され未定義エラー
- 応急処置: string_helpers.hako で src を明示的に文字列化 (""+src)
- 再現ケース: apps/tests/stage1_skip_ws_repro.hako 追加
- エラー: use of undefined value ValueId(28) in ParserBox.length(receiver=ValueId(28))

根本修正は次のcommitで実施:
- src/mir/builder/ssa/local.rs - receiver origin/type伝播強化
- Phase 25.1: Stage-1 bridge receiver bug (workaround)

lang/src/compiler/parser/scan/parser_string_utils_box.hako

@@ -2,6 +2,7 @@
 // ParserStringUtilsBox — Minimal self-contained string helpers
 // Responsibility: Backward compatibility wrapper for parser code
 // Notes: sh_core への依存で VM 差分が出たため、ここに最小実装を内包する。
+using sh_core as StringHelpers  // reuse shared helpers to align semantics
 
 static box ParserStringUtilsBox {
   // Numeric to string (minimal)
@@ -104,13 +105,7 @@ static box ParserStringUtilsBox {
   }
 
   skip_ws(src, i) {
-    if src == null { return i }
-    local n = src.length()
-    local j = i
-    loop(j < n) {
-      local ch = src.substring(j, j + 1)
-      if ParserStringUtilsBox.is_space(ch) == 1 { j = j + 1 } else { break }
-    }
-    return j
+    // Delegate to shared helper to stay consistent with Stage‑B parser semantics
+    return StringHelpers.skip_ws(src, i)
   }
 }

lang/src/runner/stage1_cli.hako

@@ -6,6 +6,12 @@
 //   - NYASH_USE_STAGE1_CLI=1             : Rust 側がこの CLI を呼ぶときに使用
 //   - STAGE1_EMIT_PROGRAM_JSON=1         : source → Program(JSON v0) を emit
 //   - STAGE1_EMIT_MIR_JSON=1             : Program(JSON v0) → MIR(JSON) を emit
+// 環境変数（env-only 仕様）:
+//   - STAGE1_SOURCE        : .hako ソースパス（FileBox 経由で読み込む）
+//   - STAGE1_SOURCE_TEXT   : ソース文字列（FileBox なしで渡すテスト用）
+//   - STAGE1_PROGRAM_JSON  : 事前生成した Program(JSON v0) のパス（emit_mir_json/run で利用）
+//   - STAGE1_BACKEND       : backend 選択（vm/llvm/pyvm、既定 vm）
+//   - STAGE1_CLI_DEBUG     : debug ログを有効化
 
 using lang.compiler.build.build_box as BuildBox
 using lang.compiler.entry.using_resolver_box as Stage1UsingResolverBox
@@ -224,11 +230,20 @@ static box Stage1Cli {
     }
 
     // Default: run path (mode == "run")
-    if source == null || source == "" {
-      print("[stage1-cli] run: source path is required (set STAGE1_SOURCE)")
-      return 96
+    local prog_json = null
+    if prog_path != null && prog_path != "" {
+      prog_json = me._read_file("[stage1-cli] run", prog_path)
+    } else {
+      if source == null || source == "" {
+        if source_text != null && source_text != "" {
+          source = source_text
+        } else {
+          print("[stage1-cli] run: source path is required (set STAGE1_SOURCE)")
+          return 96
+        }
+      }
+      prog_json = me.emit_program_json(source)
     }
-    local prog_json = me.emit_program_json(source)
     if prog_json == null { return 96 }
     return me.run_program_json(prog_json, backend)
   }

lang/src/shared/common/string_helpers.hako

@@ -168,17 +168,20 @@ static box StringHelpers {
   // Skip whitespace from position i
   skip_ws(src, i) {
     if src == null { return i }
-    local n = src.length()
+    // Canonicalize to string to avoid mis-typed receivers in static boxes
+    local s = "" + src
+    local n = s.length()
+    local j = i
     local cont = 1
     local guard = 0
     local max = 100000
     loop(cont == 1) {
-      if guard > max { return i } else { guard = guard + 1 }
-      if i < n {
-        if me.is_space(src.substring(i, i+1)) { i = i + 1 } else { cont = 0 }
+      if guard > max { return j } else { guard = guard + 1 }
+      if j < n {
+        if me.is_space(s.substring(j, j+1)) { j = j + 1 } else { cont = 0 }
       } else { cont = 0 }
     }
-    return i
+    return j
   }
 
   // Find last occurrence of pattern in string (backward search)