fix(gitea): make gitea-releases executable and correct misleading domain claims

gitea-releases was the weakest skill in the plugin: no allowed-tools, no
owner/repo resolution, and a checkbox list where a dispatch table belongs, so
an agent reaching it had to guess both its permissions and its inputs. The
id-vs-tag_name trap — deleting by tag name where the API wants the numeric id —
is restored as an explicit Gotcha because it destroys the wrong release
silently.

Elsewhere the `exclusive` flag was documented on the wrong side of the
read/write split, and label data from one instance was presented as though it
were universal, which invites an agent to assume a taxonomy that does not
exist on the target repo. rename_branch was missing from the branch surface.
Reference prose and fences are cleaned up in passing.

plugins/gitea/skills/gitea-workflow/README.md

@@ -8,7 +8,7 @@ This skill is the conversational front door to the Gitea suite — it replaces t
 
 ## Usage
 
-```
+```text
 /gitea-workflow
 ```