feat: initial Minipaste

- MinIO-backed paste storage with 8-char base62 IDs
- Paste expiry (1m, 1h, 1d, 1w, never) stored in object metadata
- Raw plain-text endpoint at /raw/:id
- Syntax highlighting in editor and paste view via highlight.js
- In-editor highlight overlay with live language switching
- Download button with correct file extension per language
- Auto-redirect to paste after creation

.env.example

@@ -0,0 +1,9 @@
+PORT=3000
+
+# MinIO connection
+MINIO_ENDPOINT=localhost
+MINIO_PORT=9000
+MINIO_USE_SSL=false
+MINIO_ACCESS_KEY=minioadmin
+MINIO_SECRET_KEY=minioadmin
+MINIO_BUCKET=pastes