Bridge v1 negatives (Method/Constructor/ModuleFunction) + BuildBox skeleton

- Add v1 bridge negative canaries (opt-in via SMOKES_ENABLE_BRIDGE_CANON):
  - canonicalize_method_missing_receiver_negative_vm.sh
  - canonicalize_constructor_missing_boxtype_negative_vm.sh
  - canonicalize_modulefn_unsupported_negative_vm.sh
- Add BuildBox skeleton under lang/src/compiler/build (README + build_box.hako)
  - Provides interface for emit/verify plan; real wiring to be added incrementally

tools/smokes/v2/profiles/quick/core/bridge/canonicalize_constructor_missing_boxtype_negative_vm.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+# canonicalize_constructor_missing_boxtype_negative_vm.sh — v1 bridge Constructor missing box_type should fail
+
+set -euo pipefail
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+if ROOT_GIT=$(git -C "$SCRIPT_DIR" rev-parse --show-toplevel 2>/dev/null); then
+  ROOT="$ROOT_GIT"
+else
+  ROOT="$(cd "$SCRIPT_DIR/../../../../../../../../.." && pwd)"
+fi
+source "$ROOT/tools/smokes/v2/lib/test_runner.sh"
+require_env || exit 2
+
+if [ "${SMOKES_ENABLE_BRIDGE_CANON:-0}" != "1" ]; then
+  echo "[SKIP] canonicalize_constructor_missing_boxtype_negative_vm (SMOKES_ENABLE_BRIDGE_CANON=1)"
+  exit 0
+fi
+
+json_path="/tmp/ny_v1_ctor_missing_type_$$.json"
+cat >"$json_path" <<'JSON'
+{"schema_version":"1.0","functions":[{"name":"main","blocks":[{"id":0,"instructions":[
+  {"op":"mir_call","dst":1,
+    "callee":{"type":"Constructor"},
+    "args":[]},
+  {"op":"ret"}
+]}]}]}
+JSON
+
+set +e
+HAKO_NYVM_V1_DOWNCONVERT=1 "$NYASH_BIN" --json-file "$json_path" >/dev/null 2>&1
+rc=$?
+set -e
+rm -f "$json_path"
+
+if [ "$rc" != 0 ]; then
+  echo "[PASS] canonicalize_constructor_missing_boxtype_negative_vm"
+else
+  echo "[FAIL] canonicalize_constructor_missing_boxtype_negative_vm (unexpected rc=0)" >&2
+  exit 1
+fi
+

tools/smokes/v2/profiles/quick/core/bridge/canonicalize_method_missing_receiver_negative_vm.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+# canonicalize_method_missing_receiver_negative_vm.sh — v1 bridge Method without receiver should fail
+
+set -euo pipefail
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+if ROOT_GIT=$(git -C "$SCRIPT_DIR" rev-parse --show-toplevel 2>/dev/null); then
+  ROOT="$ROOT_GIT"
+else
+  ROOT="$(cd "$SCRIPT_DIR/../../../../../../../../.." && pwd)"
+fi
+source "$ROOT/tools/smokes/v2/lib/test_runner.sh"
+require_env || exit 2
+
+if [ "${SMOKES_ENABLE_BRIDGE_CANON:-0}" != "1" ]; then
+  echo "[SKIP] canonicalize_method_missing_receiver_negative_vm (SMOKES_ENABLE_BRIDGE_CANON=1)"
+  exit 0
+fi
+
+json_path="/tmp/ny_v1_method_missing_recv_$$.json"
+cat >"$json_path" <<'JSON'
+{"schema_version":"1.0","functions":[{"name":"main","blocks":[{"id":0,"instructions":[
+  {"op":"mir_call","dst":1,
+    "callee":{"type":"Method","method":"size"},
+    "args":[]},
+  {"op":"ret"}
+]}]}]}
+JSON
+
+set +e
+HAKO_NYVM_V1_DOWNCONVERT=1 "$NYASH_BIN" --json-file "$json_path" >/dev/null 2>&1
+rc=$?
+set -e
+rm -f "$json_path"
+
+if [ "$rc" != 0 ]; then
+  echo "[PASS] canonicalize_method_missing_receiver_negative_vm"
+else
+  echo "[FAIL] canonicalize_method_missing_receiver_negative_vm (unexpected rc=0)" >&2
+  exit 1
+fi
+

tools/smokes/v2/profiles/quick/core/bridge/canonicalize_modulefn_unsupported_negative_vm.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+# canonicalize_modulefn_unsupported_negative_vm.sh — v1 bridge ModuleFunction unsupported callee type should fail
+
+set -euo pipefail
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+if ROOT_GIT=$(git -C "$SCRIPT_DIR" rev-parse --show-toplevel 2>/dev/null); then
+  ROOT="$ROOT_GIT"
+else
+  ROOT="$(cd "$SCRIPT_DIR/../../../../../../../../.." && pwd)"
+fi
+source "$ROOT/tools/smokes/v2/lib/test_runner.sh"
+require_env || exit 2
+
+if [ "${SMOKES_ENABLE_BRIDGE_CANON:-0}" != "1" ]; then
+  echo "[SKIP] canonicalize_modulefn_unsupported_negative_vm (SMOKES_ENABLE_BRIDGE_CANON=1)"
+  exit 0
+fi
+
+json_path="/tmp/ny_v1_modulefn_unsupported_$$.json"
+cat >"$json_path" <<'JSON'
+{"schema_version":"1.0","functions":[{"name":"main","blocks":[{"id":0,"instructions":[
+  {"op":"mir_call","dst":1,
+    "callee":{"type":"ModuleFunction","module":"ArrayBox","function":"len"},
+    "args":[]},
+  {"op":"ret"}
+]}]}]}
+JSON
+
+set +e
+HAKO_NYVM_V1_DOWNCONVERT=1 "$NYASH_BIN" --json-file "$json_path" >/dev/null 2>&1
+rc=$?
+set -e
+rm -f "$json_path"
+
+if [ "$rc" != 0 ]; then
+  echo "[PASS] canonicalize_modulefn_unsupported_negative_vm"
+else
+  echo "[FAIL] canonicalize_modulefn_unsupported_negative_vm (unexpected rc=0)" >&2
+  exit 1
+fi
+