Remove mysql export that doesn't exist in patched emdash 0.9.0

The blog template's db.ts imported 'mysql' from 'emdash/db' but the
patched source only exports sqlite, libsql, and postgres adapters.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/lib/db.ts

@@ -1,4 +1,4 @@
-import { sqlite, postgres, mysql } from "emdash/db";
+import { sqlite, postgres } from "emdash/db";
 
 /**
  * Database configuration from environment variables.
@@ -26,11 +26,6 @@ export function getDatabaseConfig() {
 		return postgres({ connectionString: url });
 	}
 
-	if (url.startsWith("mysql:")) {
-		// MySQL
-		return mysql({ connectionString: url });
-	}
-
 	// Fallback to SQLite
 	console.warn(`Unknown DATABASE_URL protocol, falling back to SQLite`);
 	return sqlite({ url: "file:./storage/data.db" });