src/dimensional.carp: `transpose` captures `i` (closure error blocks all tests)

All four tests under `test/` fail to compile with:

```
Can't give away the captured value 'i' at line 33, column 69 in 'src/dimensional.carp'. Captured values can be borrowed with `&` or copied with `@&`, not moved.
```

The offending form:

```carp
(defn transpose [f]
(tabulate &(fn [i] (smap &(fn [x] ((lookup x) i)) f))))
```

The inner closure captures `i` by move when it needs to be borrowed (`&i`) or copied (`@&i`).

The test runner (`test-all.sh`) doesn't propagate `carp -x` exit codes through the loop, so the failure has been silently swallowed in CI.