Feature Request: Add `update` method for GeospatialIndex

### Feature Request: Add `update` method for GeospatialIndex

Hi Convex team 👋

I'm building a **dating application** using `@convex/geospatial`, and currently, it seems that the API only supports:

```ts
geospatial.insert()
geospatial.remove()
````

Here’s an example of what I’m doing:

```ts
const geospatial = new GeospatialIndex>(components.geospatial)

await geospatial.insert(ctx, profile._id, {
latitude: profile.location.latitude,
longitude: profile.location.longitude,
}, {
lookingFor, // "male" | "female" | "both"
})
```

However, my users can later update their `lookingFor` field (e.g., from `"male"` to `"both"`).
Right now, I have to remove and reinsert the record to achieve this, which feels inefficient.

---

### 🧩 Feature Request

It would be great if the library supported an **`update` method**, such as:

```ts
await geospatial.update(ctx, profile._id, {
latitude,
longitude,
}, {
lookingFor,
})
```

This would make it easier to update metadata or location without needing to remove and reinsert the record.

---