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_test.go

@@ -104,6 +104,38 @@ func TestUpdateRepo(t *testing.T) {
 	assert.Equal(t, "updated", r.Description)
 }
 
+func TestGetTree(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		assert.Equal(t, "/api/v1/repos/mathias/infra/git/trees/main", r.URL.Path)
+		assert.Equal(t, "1", r.URL.Query().Get("recursive"))
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{"sha":"abc","url":"http://x","tree":[{"path":"README.md","type":"blob","sha":"def","size":13},{"path":"internal","type":"tree","sha":"ghi"}],"truncated":false}`))
+	}))
+	defer srv.Close()
+
+	c := gitea.NewClient(srv.URL, "tok")
+	tree, err := c.GetTree(context.Background(), "mathias", "infra", "main", true)
+	require.NoError(t, err)
+	assert.Equal(t, "abc", tree.SHA)
+	require.Len(t, tree.Tree, 2)
+	assert.Equal(t, "README.md", tree.Tree[0].Path)
+	assert.Equal(t, "blob", tree.Tree[0].Type)
+	assert.Equal(t, int64(13), tree.Tree[0].Size)
+}
+
+func TestUpdateTopics(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		assert.Equal(t, http.MethodPut, r.Method)
+		assert.Equal(t, "/api/v1/repos/mathias/infra/topics", r.URL.Path)
+		w.WriteHeader(http.StatusNoContent)
+	}))
+	defer srv.Close()
+
+	c := gitea.NewClient(srv.URL, "tok")
+	err := c.UpdateTopics(context.Background(), "mathias", "infra", []string{"go", "mcp", "gitops"})
+	require.NoError(t, err)
+}
+
 func TestDefaultBranchCachesAcrossCalls(t *testing.T) {
 	var hits int32
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {