Remove SB column and improve widget formatting

Services widget:
- Remove SB (sandbox) column and related formatting function
- Fix quota formatting to show decimals when needed (1.5G not 1G)
- Remove spaces in unit display (128MB not 128 MB)

Storage widget:
- Change usage format to 23GB (932GB) for better readability

Documentation:
- Add NixOS configuration update process to CLAUDE.md

CLAUDE.md

@@ -364,3 +364,49 @@ NEVER implement code without first getting explicit user agreement on the approa
 - ✅ "Implement maintenance mode for backup operations"
 - ✅ "Restructure storage widget with improved layout"
 - ✅ "Update CPU thresholds to production values"
+
+## NixOS Configuration Updates
+
+When code changes are made to cm-dashboard, the NixOS configuration at `~/nixosbox` must be updated to deploy the changes.
+
+### Update Process
+
+1. **Get Latest Commit Hash**
+   ```bash
+   git log -1 --format="%H"
+   ```
+
+2. **Update NixOS Configuration**
+   Edit `~/nixosbox/hosts/common/cm-dashboard.nix`:
+   ```nix
+   src = pkgs.fetchgit {
+     url = "https://gitea.cmtec.se/cm/cm-dashboard.git";
+     rev = "NEW_COMMIT_HASH_HERE";
+     sha256 = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA="; # Placeholder
+   };
+   ```
+
+3. **Get Correct Source Hash**
+   Build with placeholder hash to get the actual hash:
+   ```bash
+   cd ~/nixosbox
+   nix-build --no-out-link -E 'with import <nixpkgs> {}; fetchgit { 
+     url = "https://gitea.cmtec.se/cm/cm-dashboard.git"; 
+     rev = "NEW_COMMIT_HASH"; 
+     sha256 = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA="; 
+   }' 2>&1 | grep "got:"
+   ```
+
+4. **Update Configuration with Correct Hash**
+   Replace the placeholder with the hash from the error message.
+
+5. **Commit NixOS Configuration**
+   ```bash
+   cd ~/nixosbox
+   git add hosts/common/cm-dashboard.nix
+   git commit -m "Update cm-dashboard to latest version (SHORT_HASH)"
+   git push
+   ```
+
+6. **Rebuild System**
+   The user handles the system rebuild step - this cannot be automated.