test(web): the language refusal asserts its message, not a word the form always contains (#61)

Found by the PR #62 review: the message could be replaced with 'x' and the test stayed green.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/web/uploads_language_handler_test.go

@@ -109,7 +109,7 @@ func TestUploadPost_ALanguageOutsideTheClosedSetIsRefusedBeforeAnythingIsSpooled
 			rows, err := newStore(t).ListUploads(context.Background(), userID)
 			require.NoError(t, err)
 			assert.Empty(t, rows, "and must leave no row")
-			assert.Contains(t, body(t, rec), "language")
+			assert.Contains(t, body(t, rec), "Choose a language from the list.")
 		})
 	}
 }