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/branches.md

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+---
+topic: branches
+source_keys:
+  - gitea-mcp-repo
+  - gitea-mcp-slim-go
+---
+
+# Branch operations
+
+Call signatures below were verified live against the deployed `gitea-mcp` server via `ToolSearch`
+at authoring time, not copied from research docs — this is deliberate: research docs are generated
+from source code at a point in time and can drift from the server actually deployed. Re-verify
+against the live schema if these tools appear to behave differently than documented here.
+
+## `list_branches`
+
+**Parameters:**
+- `owner` (string, required)
+- `repo` (string, required)
+- `page` (number, optional, default: `1`)
+- `per_page` (number, optional, default: `30`)
+
+**Call:**
+```
+list_branches owner: <owner> repo: <repo>
+```
+
+**Response:** one object per branch: `name`, `protected` (bool), `commit_sha` (present when the
+underlying commit data is available).
+
+Paginate if you need the full list (see Gotchas in SKILL.md) — iterate `page` until the returned
+count is less than `per_page`.
+
+## `create_branch`
+
+**Parameters:**
+- `owner` (string, required)
+- `repo` (string, required)
+- `branch` (string, required) — new branch name
+- `old_branch` (string, optional) — source branch; if omitted, defaults to the repo's default
+  branch server-side (not necessarily your current local checkout)
+
+**Call:**
+```
+create_branch owner: <owner> repo: <repo> branch: <new-name> old_branch: <source-branch>
+```
+
+Default dispatch: if the user gives a base ("branch off of X", "from X"), pass it as `old_branch`.
+If they don't specify a base and you're mid-task on a local branch, pass your current branch
+(`git branch --show-current`) as `old_branch` so the new branch forks from where you're actually
+working, rather than silently falling back to the repo default. If neither applies (e.g. a fresh
+top-level request with no working branch context), omit `old_branch` and let it default server-side.
+
+A branch name collision returns `409 Conflict`.
+
+## `delete_branch`
+
+**Parameters:**
+- `owner` (string, required)
+- `repo` (string, required)
+- `branch` (string, required)
+
+**Call:**
+```
+delete_branch owner: <owner> repo: <repo> branch: <name>
+```
+
+Before calling this, see the hard-refusal Gotcha in SKILL.md. If the target branch's name isn't
+obviously a scratch/feature branch, call `list_branches` first and check `protected` on the
+matching entry — name-matching `main`/`master` alone isn't authoritative, since a repo can protect
+a differently-named default branch. Confirm explicitly with the user before deleting anything
+protected, every time, regardless of how the request is phrased.
+
+## Token scope
+
+`list_branches` works with `write:issue` alone. `create_branch` and `delete_branch` need
+`write:repository`. All three are verified working empirically under a token with both scopes
+(`write:issue` + `write:repository`).

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

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+---
+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.

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

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+# Sources
+
+**Note on call signatures:** per `docs/adr/0011-gitea-skill-deep-modules.md`, the tool parameter
+signatures in `references/branches.md` and `references/commits.md` were re-verified live via
+`ToolSearch` against the deployed `gitea-mcp` server at authoring time — they are not copied
+verbatim from `api-reference.md` below. This resolves issue #6 comment #849's root-cause finding
+that a prior skill was authored from API docs that had drifted from the actual MCP tool schema.
+The research docs cited here informed gotchas, response shapes, and workflow context, not the
+parameter lists themselves.
+
+## gitea-mcp-repo
+
+- **URL:** https://gitea.com/gitea/gitea-mcp
+- **Description:** Official gitea-mcp repository (v1.3.0); operation/*.go source files documenting all 55 MCP tools, their parameters, and CLI flags. Informed the dispatch table and pagination / 404-may-mean-403 gotchas in SKILL.md, and the list/create/delete branch and list/get commit mechanics (including 409 conflict and default-branch fallback behavior) in references/branches.md and references/commits.md.
+- **Research doc:** plugins/gitea/docs/research/docs/gitea/sources.md
+- **Contributing files:** SKILL.md, references/branches.md, references/commits.md
+- **Status:** `extracted`
+
+## gitea-mcp-slim-go
+
+- **URL:** https://gitea.com/gitea/gitea-mcp/raw/branch/main/operation/repo/slim.go
+- **Description:** Slim response shape structs from gitea-mcp source; defines exactly which fields the MCP server returns for branches (name, protected, commit_sha) and commits (sha, html_url, created, message, author), and informed get_commit's always-populated guarantee vs. list_commits' conditional fields.
+- **Research doc:** plugins/gitea/docs/research/docs/gitea/sources.md
+- **Contributing files:** references/branches.md, references/commits.md
+- **Status:** `extracted`