feat(tools): repo_tree, repo_topics_update, file_read dir fix (#14, #15, #18)

repo_tree: GET /git/trees/{ref}?recursive=1 — full recursive file tree
repo_topics_update: PUT /repos/{owner}/{repo}/topics — replace topic list
file_read: detect array response and return descriptive error for dir paths

internal/gitea/repos.go

@@ -18,6 +18,56 @@ type Repo struct {
 	Template      bool   `json:"template"`
 }
 
+type TreeEntry struct {
+	Path string `json:"path"`
+	Type string `json:"type"` // "blob" or "tree"
+	SHA  string `json:"sha"`
+	Size int64  `json:"size"`
+	URL  string `json:"url"`
+}
+
+type Tree struct {
+	SHA       string      `json:"sha"`
+	URL       string      `json:"url"`
+	Tree      []TreeEntry `json:"tree"`
+	Truncated bool        `json:"truncated"`
+}
+
+func (c *Client) GetTree(ctx context.Context, owner, repo, ref string, recursive bool) (*Tree, error) {
+	path := fmt.Sprintf("/api/v1/repos/%s/%s/git/trees/%s", owner, repo, url.PathEscape(ref))
+	if recursive {
+		path += "?recursive=1"
+	}
+	body, status, err := c.GetJSON(ctx, path)
+	if err != nil {
+		return nil, err
+	}
+	if err := MapStatus(status, body); err != nil {
+		return nil, err
+	}
+	var t Tree
+	if err := json.Unmarshal(body, &t); err != nil {
+		return nil, err
+	}
+	return &t, nil
+}
+
+func (c *Client) UpdateTopics(ctx context.Context, owner, repo string, topics []string) error {
+	path := fmt.Sprintf("/api/v1/repos/%s/%s/topics", owner, repo)
+	body, err := json.Marshal(map[string][]string{"topics": topics})
+	if err != nil {
+		return err
+	}
+	resp, status, err := c.PutJSON(ctx, path, body)
+	if err != nil {
+		return err
+	}
+	if status == 204 {
+		return nil
+	}
+	return MapStatus(status, resp)
+}
+
 func (c *Client) ListRepos(ctx context.Context, owner string, page, limit int) ([]Repo, error) {
 	if page < 1 {
 		page = 1