fix(scrape): audit and salvage corrupt archive JSON

Add audit-archive-json and salvage-truncated-export helpers, skip invalid
JSON during prove snapshots, and wire an audit smoke test into CI.

scripts/tests/audit-archive-json-smoke.sh

@@ -0,0 +1,59 @@
+#!/usr/bin/env bash
+
+set -Eeuo pipefail
+
+REPO_ROOT=$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd -P)
+TMP_DIR=$(mktemp -d "${TMPDIR:-/tmp}/dce-audit-smoke.XXXXXX")
+ARCHIVE_ROOT="$TMP_DIR/archive"
+CONFIG_PATH="$TMP_DIR/config.json"
+AUDIT="$REPO_ROOT/scripts/audit-archive-json.sh"
+
+cleanup() {
+  rm -rf "$TMP_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$ARCHIVE_ROOT/good" "$ARCHIVE_ROOT/bad"
+
+cat >"$ARCHIVE_ROOT/good/valid [111].json" <<'JSON'
+{"guild":{"id":"1","name":"g"},"channel":{"id":"111","name":"c"},"messages":[],"messageCount":0}
+JSON
+
+printf '{"messages":[\n' >"$ARCHIVE_ROOT/bad/truncated [222].json"
+
+cat >"$CONFIG_PATH" <<JSON
+{
+  "archive_root": "$ARCHIVE_ROOT",
+  "targets": [
+    {
+      "name": "demo",
+      "kind": "guild",
+      "output_dir": "$ARCHIVE_ROOT/good",
+      "enabled": true
+    },
+    {
+      "name": "broken",
+      "kind": "guild",
+      "output_dir": "$ARCHIVE_ROOT/bad",
+      "enabled": true
+    }
+  ]
+}
+JSON
+
+DCE_CONFIG_FILE="$CONFIG_PATH" "$AUDIT" --target demo
+
+set +e
+broken_output=$(DCE_CONFIG_FILE="$CONFIG_PATH" "$AUDIT" --target broken 2>&1)
+broken_status=$?
+set -e
+if [[ "$broken_status" -eq 0 ]]; then
+  printf 'ERROR: audit should fail for target with invalid JSON\n' >&2
+  exit 1
+fi
+if ! grep -q 'INVALID' <<<"$broken_output"; then
+  printf 'ERROR: audit output missing INVALID marker\n' >&2
+  exit 1
+fi
+
+printf 'audit-archive-json-smoke: OK\n'