fix(energy): deliver prototype-aligned hydrogen board and acceptance fixes

Co-authored-by: HiFox Agent <agents-noreply@hifox.com>

src/server/hydrogen-read-only.ts

@@ -0,0 +1,7 @@
+const READ_ONLY_SQL = /^\s*(SELECT|SHOW|WITH|EXPLAIN)\b/i;
+
+export function assertHydrogenReadOnlySql(statement: string, enabled: boolean) {
+  if (enabled && !READ_ONLY_SQL.test(statement)) {
+    throw new Error('HYDROGEN_DB_READ_ONLY blocks non-read SQL');
+  }
+}