fix(api): add missing ssh_keys router import

The ssh_keys module was imported in main.py but missing from api/__init__.py,
potentially causing import issues. Added to ensure all API routers are
explicitly declared and available.

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

backend/app/api/__init__.py

@@ -9,10 +9,11 @@ from . import settings
 from . import notifications
 from . import users
 from . import workspaces
+from . import ssh_keys
 
 __all__ = [
     "auth",
-    "dashboard", 
+    "dashboard",
     "proxmox",
     "templates",
     "ipam",
@@ -21,4 +22,5 @@ __all__ = [
     "notifications",
     "users",
     "workspaces",
+    "ssh_keys",
 ]