terra: Add support for tile_apply()

**terra** (>= 1.9-25) [2026-05-06] supports:

```r
future::plan(future::multisession, workers=2)
out6 <- tile_apply(r, function(x) x * 2, cores="future")
```

We can easily add support for:

```r
out6 <- tile_apply(r, function(x) x * 2) |> futurize()
```

Start by locating how futurize handles existing terra operations and how the |> futurize() entry point translates calls. Use the tile_apply() example in the issue as the acceptance case, and add support so the pipeline form provides the same parallel behavior as the explicit cores="future" form.

Written by the indexing model from the issue text.