[AUTOMATIC] Release/10.19.1 (#4113)

**This is an automatic release.**

## RevenueCatUI SDK
### Paywallsv2
#### 🐞 Bugfixes
* fix(paywalls): add user context to custom web checkout URLs (#4107)
via Cesar de la Vega (@vegaro)
* fix(paywalls): keep the subscribe button working after a cancelled
purchase (#4071) via Facundo Menzella (@facumenzella)

### 🔄 Other Changes
* fix(checkpoints): Fix checkpoint resolution config races (#4058) via
Cesar de la Vega (@vegaro)
* Improve Checkpoints APIs (#4108) via Toni Rico (@tonidero)
* ci(danger): Clean up API notifications after move to main-only posts
(#4101) via Álvaro Brey (@AlvaroBrey)

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Release bookkeeping and docs/CI path updates only; no SDK behavior
changes in this diff.
> 
> **Overview**
> This is an **automatic release** PR that pins the repo and publishing
metadata to **10.19.1** (replacing `10.20.0-SNAPSHOT`) in `.version`,
`gradle.properties`, `Config.frameworkVersion`, and sample/test-app
`libs.versions.toml` files.
> 
> It **documents the release** by adding a **10.19.1** section to
`CHANGELOG.md` and trimming `CHANGELOG.latest.md` to match. **Docs
hosting** is updated so `docs/index.html` redirects to `10.19.1` and
CircleCI’s `docs-deploy` job syncs `docs/10.19.1` to S3.
> 
> The **user-facing fixes in this release** (already merged elsewhere)
are summarized in the changelog: Paywalls v2 fixes for custom web
checkout URLs and subscribe-after-cancelled purchase, checkpoint
resolution race fixes and API improvements, and CI Danger cleanup—not
new logic in this diff.
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
46907acf9dea1aa56495384b9d4bbcb664f236c1. Bugbot is set up for automated
code reviews on this repo. Configure
[here](https://www.cursor.com/dashboard/bugbot).</sup>
<!-- /CURSOR_SUMMARY -->