chore: fix formatting and lint errors across Makefile, backend, and adminfront

This commit addresses several linting and formatting issues that caused CI checks to fail:
- Makefile: Removed obsolete '--organize-imports-enabled' from Biome and switched to '@biomejs/biome'.
- backend: Fixed spacing and alignment issues according to gofmt.
- adminfront: Fixed multiple unused variables and imports, and configured unsafe fixes in the Biome config to remove dead code.

adminfront/scripts/serve-prod.mjs

@@ -3,7 +3,7 @@ import { createServer } from "node:http";
 import { extname, join, normalize, resolve } from "node:path";
 import { fileURLToPath } from "node:url";
 
-const rootDir = fileURLToPath(new URL("..", import.meta.url));
+const _rootDir = fileURLToPath(new URL("..", import.meta.url));
 const distDir = resolve(
   process.env.ADMINFRONT_BUILD_OUT_DIR ?? "/tmp/baron-sso-adminfront-dist",
 );