feat(gitea): add gitea-branches skill (branches + commits)

Adds plugins/gitea/skills/gitea-branches/ per ADR 0011, covering
list_branches/create_branch/delete_branch (migrated from the flat
plugins/bin/skills/gitea/ dispatch) plus list_commits/get_commit (new
read-only commit-history domain). Call signatures were re-verified live
via ToolSearch against the deployed gitea-mcp server rather than copied
from api-reference.md, per issue #6 comment #849's root-cause fix.

Bumps the gitea plugin to 1.1.0 in both manifests for the new skill.

plugins/gitea/skills/gitea-branches/references/commits.md

@@ -0,0 +1,67 @@
+---
+topic: commits
+source_keys:
+  - gitea-mcp-repo
+  - gitea-mcp-slim-go
+---
+
+# Commit operations
+
+Read-only commit history, scoped to a repo (optionally to one branch or one path). Call signatures
+below were verified live against the deployed `gitea-mcp` server via `ToolSearch` at authoring time,
+not copied from research docs, for the same drift-avoidance reason noted in `references/branches.md`.
+
+This domain has no prior skill precedent — it's new coverage added alongside branches because commit
+history is naturally scoped to a branch (a "what happened on this branch" question), not because it
+shares any tool family with branch create/delete.
+
+## `list_commits`
+
+**Parameters:**
+- `owner` (string, required)
+- `repo` (string, required)
+- `sha` (string, optional) — starting SHA or branch name; if omitted, gitea-mcp uses the repo's
+  default branch
+- `path` (string, optional) — restrict results to commits that touched this file/path
+- `page` (number, optional, default: `1`, minimum: `1`)
+- `per_page` (number, optional, default: `30`, minimum: `1`)
+
+**Call:**
+```
+list_commits owner: <owner> repo: <repo> sha: <branch-or-sha> path: <optional-path>
+```
+
+Dispatch defaults:
+- "commits on `<branch>`" → pass `<branch>` as `sha`.
+- "commits touching `<path>`" (no branch mentioned) → pass `path` alone, `sha` omitted (defaults to
+  the repo's default branch).
+- Both given → pass both; the result is history for that path, walked from that branch/SHA.
+- Neither given → omit both; this returns default-branch history, which is a reasonable default for
+  an open-ended "what's the recent history here" question.
+
+**Response:** one object per commit: `sha`, `html_url`, `created`, `message` (when available),
+`author` (`{name, email, date}`, when available).
+
+Paginate per the manual-pagination Gotcha in SKILL.md if you need more than one page of history.
+
+## `get_commit`
+
+**Parameters:**
+- `owner` (string, required)
+- `repo` (string, required)
+- `sha` (string, required)
+
+**Call:**
+```
+get_commit owner: <owner> repo: <repo> sha: <commit-sha>
+```
+
+**Response:** same shape as a `list_commits` entry, but always fully populated (`message` and
+`author` are guaranteed present, not conditional). Use this when the user asks about one specific
+commit by SHA rather than browsing history — `list_commits` entries may omit `message`/`author` in
+edge cases, `get_commit` will not.
+
+## Token scope
+
+Both tools are read-only and work with `write:issue` alone (no `write:repository` needed), verified
+empirically against the deployed server.