Rename to usync, use generic git URLs

- Rename app binary from unsbs-setup to usync-setup
- Update README to use git+ssh:// URLs for custom git servers
- Remove GitHub-specific references

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

flake.nix

@@ -81,7 +81,7 @@
         let
           pkgs = nixpkgsFor.${system};
           setupScript = pkgs.writeShellApplication {
-            name = "unsbs-setup";
+            name = "usync-setup";
             runtimeInputs = with pkgs; [
               git
               jq
@@ -105,7 +105,7 @@
                 else
                   echo "Error: Cannot find setup script"
                   echo "Run from the repo directory, or clone it first:"
-                  echo "  git clone https://github.com/YOUR_USERNAME/ultimate-notetaking-sync-backup-system.git"
+                  echo "  git clone git@your-server:you/usync.git"
                   exit 1
                 fi
               fi
@@ -115,11 +115,11 @@
         in {
           default = {
             type = "app";
-            program = "${setupScript}/bin/unsbs-setup";
+            program = "${setupScript}/bin/usync-setup";
           };
           setup = {
             type = "app";
-            program = "${setupScript}/bin/unsbs-setup";
+            program = "${setupScript}/bin/usync-setup";
           };
         }
       );