Gate‑C(Core) OOB strict fail‑fast; String VM handler normalization; JSON lint Stage‑B root fixes via scanner field boxing and BinOp operand slotify; docs + smokes update

lang/src/vm/README.md

@@ -56,6 +56,7 @@ Quick profile opt‑in switches (smokes)
 - `SMOKES_ENABLE_LOOP_COMPARE=1` — Direct↔Bridge parity for loops (sum/break/continue/nested/mixed)
 - `SMOKES_ENABLE_LOOP_BRIDGE=1` — Bridge(JSON v0) loop canaries (quiet; last numeric extraction)
 - `SMOKES_ENABLE_STAGEB_OOB=1` — Stage‑B OOB observation (array/map)
+- `SMOKES_ENABLE_OOB_STRICT=1` — Gate‑C(Core) strict OOB fail‑fast canary (`gate_c_oob_strict_fail_vm.sh`)
 - `SMOKES_ENABLE_LLVM_SELF_PARAM=1` — LLVM instruction boxes self‑param builder tests (const/binop/compare/branch/jump/ret)
 
 Deprecations
@@ -77,6 +78,12 @@ Diagnostics (stable tags)
   - `[core/mir_call] unsupported callee type: Closure`
 - Gate‑C Direct では、リーダー/検証レイヤの診断をそのまま用いる（例: `unsupported callee type (expected Extern): ModuleFunction`）。
 
+Strict OOB policy (Gate‑C)
+- Enable `HAKO_OOB_STRICT=1` (alias: `NYASH_OOB_STRICT`) to tag Array OOB as stable strings
+  (`[oob/array/get]…`, `[oob/array/set]…`).
+- With `HAKO_OOB_STRICT_FAIL=1` (alias: `NYASH_OOB_STRICT_FAIL`), Gate‑C(Core) exits non‑zero
+  if any OOB was observed during execution (no need to parse stdout in tests).
+
 Exit code differences
 - Core: 数値=rc（OS仕様により 0–255 に丸められる。例: 777 → rc=9）、エラーは非0
 - Direct: 数値出力のみ（rc=0）、エラーは非0