test(api/v2): port full v1 avatar coverage to TestAvatar

Bring the v2 avatar webtest to 1:1 parity with the v1 avatar tests so
the v1 routes and tests can be removed without losing coverage:

- link-share auth path: a request authenticated as a link-share user
  (not a regular JWT) returns 200 + non-empty image bytes, porting
  v1's TestLinkShareAvatar.
- bot user: the botmarble provider path returns 200 + SVG bytes, a
  distinct rendering v1 never exercised; asserts the marble mask id so
  it cannot silently fall through to the default placeholder.
- non-numeric size: rejected with 422 (Huma's int64 query validation)
  rather than v1's 400 ErrInvalidModel, both being client errors that
  refuse the malformed input.

pkg/webtests/huma_avatar_test.go

@@ -20,6 +20,9 @@ import (
 	"net/http"
 	"testing"
 
+	"code.vikunja.io/api/pkg/models"
+	"code.vikunja.io/api/pkg/modules/auth"
+
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -81,4 +84,68 @@ func TestAvatar(t *testing.T) {
 		assert.NotEmpty(t, rec.Body.Bytes())
 		assert.Equal(t, "image/svg+xml", rec.Header().Get("Content-Type"))
 	})
+
+	t.Run("Authenticated as a link share returns bytes and a content type", func(t *testing.T) {
+		// Ports v1's TestLinkShareAvatar: a request authenticated as a link-share
+		// user (not a regular JWT) must succeed. The avatar endpoint inherits the
+		// global security; a link-share JWT is a valid credential and resolves to a
+		// link-share web.Auth in authFromCtx, so the request must not 401. The
+		// requested username here is the synthetic link-share-1 handle (matching v1):
+		// it is not a real user row, so GetAvatarForUsername serves the empty
+		// provider's default SVG with a 200 — proving the link-share auth path works.
+		e, err := setupTestEnv()
+		require.NoError(t, err)
+
+		share := &models.LinkSharing{
+			ID:          1,
+			Hash:        "test",
+			ProjectID:   1,
+			Permission:  models.PermissionRead,
+			SharingType: models.SharingTypeWithoutPassword,
+			SharedByID:  1,
+		}
+		token, err := auth.NewLinkShareJWTAuthtoken(share)
+		require.NoError(t, err)
+
+		rec := humaRequest(t, e, http.MethodGet, "/api/v2/avatar/link-share-1", "", token, "")
+		require.Equal(t, http.StatusOK, rec.Code, "link-share auth must succeed; body: %s", rec.Body.String())
+		assert.NotEmpty(t, rec.Body.Bytes(), "avatar bytes must be returned for a link-share caller")
+		assert.NotEmpty(t, rec.Header().Get("Content-Type"), "a content type must be set")
+	})
+
+	t.Run("Bot user avatar is rendered by the botmarble provider", func(t *testing.T) {
+		// A bot user (bot_owner_id set) routes through the botmarble provider rather
+		// than its configured provider — a distinct rendering path v1's single test
+		// never exercised. It must still return 200 + non-empty bytes. botmarble
+		// renders a marble-style SVG, so the content type is image/svg+xml.
+		e, err := setupTestEnv()
+		require.NoError(t, err)
+		token := humaTokenFor(t, &testuser1)
+
+		rec := humaRequest(t, e, http.MethodGet, "/api/v2/avatar/bot-owner-a-assistant", "", token, "")
+		require.Equal(t, http.StatusOK, rec.Code, "body: %s", rec.Body.String())
+		assert.NotEmpty(t, rec.Body.Bytes(), "bot avatar bytes must be returned")
+		assert.Equal(t, "image/svg+xml", rec.Header().Get("Content-Type"), "botmarble renders an SVG")
+		// The marble mask id is unique to the (bot)marble renderer; the empty
+		// fallback SVG never contains it. Asserting on it proves IsBot() routed
+		// to botmarble rather than silently falling through to the default avatar.
+		assert.Contains(t, rec.Body.String(), "mask__marble",
+			"bot avatar must be rendered by the (bot)marble provider, not the default placeholder")
+	})
+
+	t.Run("Non-numeric size is rejected", func(t *testing.T) {
+		// v1 parses ?size with strconv.ParseInt and returns ErrInvalidModel
+		// ("Invalid size parameter") -> 400 for a non-numeric value. v2 declares
+		// Size as int64, so Huma's own request validation rejects the malformed
+		// query value before the handler runs and returns 422 Unprocessable Entity.
+		// Either client-error status proves the malformed input is refused rather
+		// than silently coerced; assert v2's actual behaviour (422).
+		e, err := setupTestEnv()
+		require.NoError(t, err)
+		token := humaTokenFor(t, &testuser1)
+
+		rec := humaRequest(t, e, http.MethodGet, "/api/v2/avatar/user1?size=notanumber", "", token, "")
+		require.Equal(t, http.StatusUnprocessableEntity, rec.Code,
+			"non-numeric size must be rejected by Huma's int64 validation; body: %s", rec.Body.String())
+	})
 }