docs: add clipboard note and update flake inputs

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

CLAUDE.md

@@ -63,6 +63,14 @@ Examples:
 - `template2: add proxmox image configuration`
 - `terraform: add VM deployment configuration`
 
+### Clipboard
+
+To copy text to the clipboard, pipe to `wl-copy` (Wayland):
+
+```bash
+echo "text" | wl-copy
+```
+
 ### NixOS Options Lookup
 
 An MCP server is available for searching and looking up NixOS option documentation. This is useful when configuring new services or options for hosts.
@@ -145,7 +153,6 @@ Template/test hosts:
 - `nixpkgs-unstable` - Unstable channel (available via overlay as `pkgs.unstable.<package>`)
 - `sops-nix` - Secrets management
 - Custom packages from git.t-juice.club:
-  - `backup-helper` - Backup automation module
   - `alerttonotify` - Alert routing
   - `labmon` - Lab monitoring