refactor: remove deployment.json and use direct selectors

- Remove deployment.json file generation from outputs.nix
- Add throw for deprecated deployment.file usage with upgrade instructions
- Remove vars data from deployment.data
- Update Machine class to use direct select() calls instead of deployment property
- Update all deployment property accesses to use direct selectors
- Add precaching for frequently accessed values in update.py:
  - Module paths for facts and vars
  - Deployment settings (requireExplicitUpdate, nixosMobileWorkaround)
  - Services and generators data
  - Secret upload locations
- This removes unnecessary JSON serialization and makes the code more composable

pkgs/clan-cli/clan_lib/machines/update.py

@@ -184,7 +184,12 @@ def deploy_machine(
 
         # retry nixos-rebuild switch if the first attempt failed
         if ret.returncode != 0:
-            is_mobile = machine.deployment.get("nixosMobileWorkaround", False)
+            try:
+                is_mobile = machine.select(
+                    "config.system.clan.deployment.nixosMobileWorkaround"
+                )
+            except Exception:
+                is_mobile = False
             # if the machine is mobile, we retry to deploy with the mobile workaround method
             if is_mobile:
                 machine.info(