Forward position parameter from /jump URL into the Explorer deep link

## Problem

The `/jump` page on `decentraland.org` accepts a `position` query parameter (e.g. `https://decentraland.org/jump?realm=italy2026.dcl.eth&position=26,18`), but the parameter is not forwarded into the `decentraland://` deep link used to open the Explorer.

When visiting `/jump?realm=italy2026.dcl.eth&position=26,18`:
- The Places API is queried by world name only (`/worlds?names=italy2026.dcl.eth`), ignoring the `position` param entirely.
- `fromPlace()` then sets the position from the scene's `base_position` (the world's default entry point), discarding the user-specified coordinates.
- The Explorer deep link always teleports the user to the world spawn instead of the targeted parcel.

This is especially problematic for **multi-scene worlds** where each scene occupies different parcels. Without position forwarding, there is no way to share a link that targets a specific scene within a world.

**Expected:** `decentraland://?realm=italy2026.dcl.eth&position=26,18` — user lands at parcel `26,18`.
**Actual:** `decentraland://?realm=italy2026.dcl.eth&position=0,0` — user lands at the world's default spawn.

Note: the native deep link `decentraland://?realm=italy2026.dcl.eth&position=26%2C18` works correctly — the problem is only in the `/jump` web page not forwarding the parameter.

## Proposed Solution

| PR | Repo | Status | Description |
|---|---|---|---|
| [#504](https://github.com/decentraland/sites/pull/504) | `decentraland/sites` | Open | Override `cardData.position` with user-specified coordinates after `fromPlace()` mapping |

## Acceptance Criteria

- [ ] `https://decentraland.org/jump?realm=italy2026.dcl.eth&position=26,18` opens the Explorer at parcel `26,18` inside that world
- [ ] `https://decentraland.org/jump?realm=world.eth` (no position) still uses the world's default `base_position`

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Requested by Pravus via Slack