feat(webhook): fire repository event on repo rename (#38641)

Repository create and delete already fire `repository` webhooks, rename
did not. This adds the `renamed` action with `changes.name.from`
carrying the previous name, and renders it in the chat converters.

Actions workflows are unaffected, they still do not trigger on rename.

AI assistance was used for the implementation and tests.

Fixes https://github.com/go-gitea/gitea/issues/34891.
Co-authored-by: roman s <roman.sukach@dust-labs.com>
Co-authored-by: silverwind <me@silverwind.io>

options/locale/locale_en-US.json

@@ -2298,7 +2298,7 @@
   "repo.settings.event_force_push": "Force Push",
   "repo.settings.event_push_desc": "Git push to a repository.",
   "repo.settings.event_repository": "Repository",
-  "repo.settings.event_repository_desc": "Repository created or deleted.",
+  "repo.settings.event_repository_desc": "Repository created, deleted, or renamed.",
   "repo.settings.event_header_issue": "Issue Events",
   "repo.settings.event_issues": "Issues",
   "repo.settings.event_issues_desc": "Issue opened, closed, reopened, edited or deleted.",