chore: dedup dead code + compress utility

- Hapus src/shared/utils/retry.ts (0 imports, dead)
- Hapus src/shared/errors/index.ts (7 classes, 0 imports)
- Hapus drizzle type exports dari schema.ts (tidak dipake)
- Hapus src/config/index.ts, redirect 8 imports langsung ke env.ts
- Ekstrak maybeCompressChunk ke shared/utils/compress.ts
- Hapus duplikasi gzipSync di upload-file.ts + chunked-storage.ts
- Lint clean, build clean

src/shared/utils/compress.ts

@@ -0,0 +1,32 @@
+/** Compression algorithm for chunked file storage. */
+export type CompressionAlgorithm = 'gzip' | null;
+
+/**
+ * Optionally compress a chunk with gzip.
+ *
+ * Compression is skipped if:
+ * - The `compress` flag is false.
+ * - The chunk is smaller than `compressionMinSizeBytes`.
+ * - The compressed result is larger than the original.
+ *
+ * @param chunk - The raw chunk buffer.
+ * @param compress - Whether compression is enabled.
+ * @param compressionMinSizeBytes - Minimum chunk size to attempt compression.
+ * @returns The (possibly compressed) bytes and the algorithm used.
+ */
+export const maybeCompressChunk = (
+  chunk: Buffer,
+  compress: boolean,
+  compressionMinSizeBytes: number,
+): { bytes: Buffer; compressionAlgorithm: CompressionAlgorithm } => {
+  if (!compress || chunk.byteLength < compressionMinSizeBytes) {
+    return { bytes: chunk, compressionAlgorithm: null };
+  }
+
+  const gzipped = Bun.gzipSync(chunk);
+  if (gzipped.byteLength >= chunk.byteLength) {
+    return { bytes: chunk, compressionAlgorithm: null };
+  }
+
+  return { bytes: gzipped, compressionAlgorithm: 'gzip' };
+};