Make API endpoints compatible with Vultr API v2 format

- Change auth from X-API-Key header to Authorization: Bearer format
- Add /v2 prefix to all endpoints to match Vultr API URL structure
- Fix router paths (dns, firewall) to avoid duplicate path segments
- Split VPC 2.0 into separate router at /v2/vpc2

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

server/routers/__init__.py

@@ -10,6 +10,7 @@ from . import (
     block_storage,
     reserved_ips,
     vpc,
+    vpc2,
     load_balancers,
     bare_metal,
     backups,
@@ -29,6 +30,7 @@ __all__ = [
     "block_storage",
     "reserved_ips",
     "vpc",
+    "vpc2",
     "load_balancers",
     "bare_metal",
     "backups",