feat(db): add D1 query utilities

- query/queryOne/execute/batch helpers
- saas.* shortcuts for blackroad-saas
- agents.* shortcuts for agent-registry

src/utils/db.ts

@@ -0,0 +1,65 @@
+import type { Env } from "../types/env";
+
+/**
+ * D1 Database utilities for BlackRoad OS
+ */
+
+// Generic query helper with error handling
+export async function query<T = unknown>(
+  db: D1Database,
+  sql: string,
+  params: unknown[] = []
+): Promise<T[]> {
+  const result = await db.prepare(sql).bind(...params).all<T>();
+  return result.results;
+}
+
+// Single row query
+export async function queryOne<T = unknown>(
+  db: D1Database,
+  sql: string,
+  params: unknown[] = []
+): Promise<T | null> {
+  const result = await db.prepare(sql).bind(...params).first<T>();
+  return result;
+}
+
+// Execute (INSERT/UPDATE/DELETE)
+export async function execute(
+  db: D1Database,
+  sql: string,
+  params: unknown[] = []
+): Promise<D1Result> {
+  return db.prepare(sql).bind(...params).run();
+}
+
+// Batch execute
+export async function batch(
+  db: D1Database,
+  statements: { sql: string; params?: unknown[] }[]
+): Promise<D1Result[]> {
+  const prepared = statements.map((s) =>
+    db.prepare(s.sql).bind(...(s.params || []))
+  );
+  return db.batch(prepared);
+}
+
+// SaaS DB shortcuts
+export const saas = {
+  query: <T>(env: Env, sql: string, params?: unknown[]) =>
+    query<T>(env.DB_SAAS, sql, params),
+  queryOne: <T>(env: Env, sql: string, params?: unknown[]) =>
+    queryOne<T>(env.DB_SAAS, sql, params),
+  execute: (env: Env, sql: string, params?: unknown[]) =>
+    execute(env.DB_SAAS, sql, params),
+};
+
+// Agent Registry DB shortcuts  
+export const agents = {
+  query: <T>(env: Env, sql: string, params?: unknown[]) =>
+    query<T>(env.DB_AGENTS, sql, params),
+  queryOne: <T>(env: Env, sql: string, params?: unknown[]) =>
+    queryOne<T>(env.DB_AGENTS, sql, params),
+  execute: (env: Env, sql: string, params?: unknown[]) =>
+    execute(env.DB_AGENTS, sql, params),
+};