Switch SQLite to WAL mode and increase busy_timeout to 30s

WAL (Write-Ahead Logging) allows concurrent readers alongside
a single writer, eliminating SQLITE_BUSY errors in multi-process
deployments (gateway + MCP servers + Claude Code). Previously
used delete journal mode where any writer blocked all readers.

busy_timeout increased from 5s to 30s as a safety net for the
rare case where write contention still occurs under WAL.

Author: Kevin Hopper

servers/db.js

@@ -127,7 +127,10 @@ export async function ensureColumn(db, table, column, type) {
 export function createDbClient(dbPath) {
   const filePath = dbPath || process.env.CROW_DB_PATH || resolve(resolveDataDir(), "crow.db");
   const client = createClient({ url: `file:${filePath}` });
-  client.execute("PRAGMA busy_timeout = 5000").catch(err =>
+  client.execute("PRAGMA journal_mode = WAL").catch(err =>
+    console.warn("[db] Failed to set WAL mode:", err.message)
+  );
+  client.execute("PRAGMA busy_timeout = 30000").catch(err =>
     console.warn("[db] Failed to set busy_timeout:", err.message)
   );
   return client;