feat: add manual trigger to release-highlights workflow

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: lostindark

.github/workflows/release-highlights.lock.yml

@@ -2,6 +2,7 @@
 name: Release Highlights
 description: Generate AI-powered release highlights and prepend to draft release
 on:
+  workflow_dispatch:
   workflow_run:
     workflows: ["Release"]
     types: [completed]

.github/workflows/release-highlights.md

@@ -4,7 +4,7 @@ on:
   workflow_dispatch:
     inputs:
       version:
-        description: 'Version to release (e.g. 0.12.162)'
+        description: 'Version to release (e.g. 1.0.0)'
         required: true
         type: string