chore(nix): add manual workflow trigger and update vendorHash

- Add workflow_dispatch trigger to nix-update-hash workflow
- Update vendorHash to match current dependencies

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

Author: drewr

.github/workflows/nix-update-hash.yaml

@@ -6,6 +6,7 @@ on:
       - 'go.sum'
     branches-ignore:
       - 'nix-update-hash/*'
+  workflow_dispatch:
 
 jobs:
   update-hash:

flake.nix

@@ -41,7 +41,7 @@
             # Hash of Go module dependencies.
             # Update this after changing go.mod/go.sum:
             #   task nix-update-hash
-            vendorHash = "sha256-xxlYC74qdbF4VS3tqbEm78SHQYDS5vIsypZZ8dDg2GM=";
+            vendorHash = "sha256-Hj72B7lra2qU+Kj9DKP9P8/AJ3Z2p6MRTikfiSnZkO4=";
 
             ldflags = [
               "-s"