chore(llama-swap): update Genesis to v7.69, add cliff 2 optimizations

- Bump Genesis pin from fc89395 to 2db18df (v7.69)
- Add PN32 GDN chunked prefill and PN34 workspace lock relax env vars
- Replace patch_workspace_lock_disable with patch_inputs_embeds_optional
- Remove setup-time PN25/PN30 patches (folded into v7.69 natively)
- Switch patch base URL to v7.69-cliff2-test branch
- Lower GPU memory utilization to 0.93 for long-text variant
- Remove python3 from preflight check prerequisites
- Add printing service to lin-va-thinkpad

systems/x86_64-linux/lin-va-thinkpad/default.nix

@@ -57,6 +57,7 @@ in
     };
 
     services = {
+      printing = enabled;
       openssh = enabled;
       tailscale = enabled;
       avahi = enabled;