Rename repo references from usync to grapho

Update README and flake.nix to use grapho as the repo name
in all git URLs and examples.

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

README.md

@@ -12,11 +12,11 @@ A NixOS-based system for managing the three types of data in a computer:
 
 ```bash
 # One-command setup from any git server
-nix run 'git+ssh://git@your-server/you/usync.git'
+nix run 'git+ssh://git@your-server/you/grapho.git'
 
 # Or clone first, then run
-git clone git@your-server:you/usync.git
-cd usync
+git clone git@your-server:you/grapho.git
+cd grapho
 nix run .
 ```
 
@@ -26,8 +26,8 @@ nix run .
 
 ```bash
 # 1. Clone the repo
-git clone git@your-server:you/usync.git
-cd usync
+git clone git@your-server:you/grapho.git
+cd grapho
 
 # 2. Run setup (one command - includes all dependencies)
 nix run .
@@ -38,7 +38,7 @@ nix run .
 
 # 4. Push config to your git server
 cd ~/.config/usync/config
-git remote add origin git@your-server:you/usync-config.git
+git remote add origin git@your-server:you/grapho-config.git
 git push -u origin main
 ```
 
@@ -46,11 +46,11 @@ git push -u origin main
 
 ```bash
 # One command from your git server
-nix run 'git+ssh://git@your-server/you/usync.git'
+nix run 'git+ssh://git@your-server/you/grapho.git'
 # Choose option [2], enter your git URL and age key
 
 # Or non-interactively:
-git clone git@your-server:you/usync.git && cd usync
+git clone git@your-server:you/grapho.git && cd grapho
 nix run . -- <config-git-url> <your-age-key>
 ```
 
@@ -78,10 +78,10 @@ Add to your flake.nix inputs, then import the module:
 
 ```nix
 {
-  inputs.usync.url = "git+ssh://git@your-server/you/usync.git";
+  inputs.grapho.url = "git+ssh://git@your-server/you/grapho.git";
 
   # In your configuration:
-  imports = [ inputs.usync.nixosModules.default ];
+  imports = [ inputs.grapho.nixosModules.default ];
 }
 ```