Fix missing redraw upon resetting blueprint (#5262)

### What

Previously, many parts of the viewer only refresh after moving the
cursor. Just clicking the reset button and not moving the mouse left
things in an odd state.

Can't screenshot since pressing the screenshot shortcut causes a redraw
:)


### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using newly built examples:
[app.rerun.io](https://app.rerun.io/pr/5262/index.html)
* Using examples from latest `main` build:
[app.rerun.io](https://app.rerun.io/pr/5262/index.html?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[app.rerun.io](https://app.rerun.io/pr/5262/index.html?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG
* [x] If applicable, add a new check to the [release
checklist](https://github.com/rerun-io/rerun/blob/main/tests/python/release_checklist)!

- [PR Build Summary](https://build.rerun.io/pr/5262)
- [Docs
preview](https://rerun.io/preview/642d07a4d446ee3fed0f7cd885bd00a11f143a67/docs)
<!--DOCS-PREVIEW-->
- [Examples
preview](https://rerun.io/preview/642d07a4d446ee3fed0f7cd885bd00a11f143a67/examples)
<!--EXAMPLES-PREVIEW-->
- [Recent benchmark results](https://build.rerun.io/graphs/crates.html)
- [Wasm size tracking](https://build.rerun.io/graphs/sizes.html)

crates/re_viewer/src/app.rs

@@ -375,6 +375,7 @@ impl App {
                 // at the beginning of the next frame.
                 re_log::debug!("Reset blueprint");
                 store_hub.clear_current_blueprint();
+                egui_ctx.request_repaint(); // Many changes take a frame delay to show up.
             }
             SystemCommand::UpdateBlueprint(blueprint_id, updates) => {
                 // We only want to update the blueprint if the "inspect blueprint timeline" mode is

examples/python/rrt-star/README.md

@@ -3,7 +3,7 @@ title = "RRT*"
 tags = ["2D"]
 description = "Visualization of the path finding algorithm RRT* in a simple environment."
 thumbnail= "https://static.rerun.io/rrt-star/4d4684a24eab7d5def5768b7c1685d8b1cb2c010/full.png"
-thumbnail_dimensions = [480, 360]
+thumbnail_dimensions = [1496, 840]
 -->
 
 <picture>