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-issues/references/search.md

@@ -22,12 +22,12 @@ time (see `references/sources.md`) — confirmed to match `api-reference.md`.
 - `per_page` (number, optional, default `30`)
 
 **Call:**
-```
+```text
 search_issues query: <text>
 ```
 
 **Narrowing the search:**
-```
+```text
 search_issues query: <text> owner: <owner> state: "open" type: "pulls" labels: "bug,urgent"
 ```