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/references/skill-index.md

@@ -13,7 +13,7 @@ The request names a capability but not obviously which skill owns it. Find the o
 | `gitea-issues` | List/read/create/update issues, comments, search across issues and PRs. Composes `gitea-labels-milestones` for label/milestone resolution. |
 | `gitea-labels-milestones` | Label and milestone CRUD, label inference from conversation context, resolving names/titles to the numeric IDs writes require. Cross-cutting — used by both `gitea-issues` and `gitea-prs`. |
 | `gitea-prs` | List/read/create/update/merge PRs, code reviews. Composes `gitea-labels-milestones` the same way `gitea-issues` does. |
-| `gitea-branches` | Branch list/create/delete, plus commit history (list commits, get a single commit by SHA). |
+| `gitea-branches` | Branch list/create/rename/delete, plus commit history (list commits, get a single commit by SHA). |
 | `gitea-files` | Read/write/delete individual files, list a directory, walk the full repo tree. |
 | `gitea-releases` | Release and tag CRUD — draft/prerelease flags, release notes, semver tags. |