Match semantic IDs (e.g. KS-10) without requiring OP# prefix

Bare numeric IDs like #10 still require OP# to avoid collision with
Gitea issue numbers. Semantic identifiers (PROJ-42 style) are
unambiguous and matched with or without the prefix, as well as via
full OpenProject URL.

Update the tab empty-state message accordingly.

config/locales/js-en.yml

@@ -46,7 +46,7 @@ en:
           title: Quick snippets for Git
         title: "Pull requests"
       tab_prs:
-        empty: There are no pull requests linked yet. Link an existing PR by using the code <code>OP#%{wp_id}</code> in the PR title/description or create a new PR.
+        empty: There are no pull requests linked yet. Reference this work package in the PR title or description using its ID (e.g. <code>%{wp_id}</code>) or a full OpenProject URL.
       updated_on: Updated on
       work_packages:
         tab_name: "Gitea"