Add shape and label styling tutorial

New tutorials/styling_shapes_and_labels.ipynb covering the fill/outline
styling surface of render_shapes and render_labels on the blobs dataset:

- fill_alpha for both shapes and labels
- the outline bool toggle (restored for shapes and labels in #750) with
  outline_width / outline_color / outline_alpha
- hollow shapes (transparent fill + outline)
- scale for resizing shape geometries about their centroids
- segmentation boundaries on labels via outline + contour_px, and the
  translucent-fill-plus-outline overlay over an image

Executed against spatialdata-plot v0.4.1; committed with outputs. Adds the
gallery card + toctree entry and a thumbnail. Deliberately leaves color=/
palette/groups to the colour tutorial and points styling to as_points.

Author: timtreis

_static/img/styling_shapes_and_labels.png

@@ -54,6 +54,16 @@ Add a physical scalebar with `scalebar_dx`, choose units, and style
 placement, colour, length and fonts through `scalebar_params`.
 :::
 
+:::{grid-item-card} Styling shapes and labels
+:link: /notebooks/tutorials/styling_shapes_and_labels
+:link-type: doc
+:img-top: /notebooks/_static/img/styling_shapes_and_labels.png
+
+Control how shapes and labels are drawn: `fill_alpha`, the `outline`
+toggle with `outline_width`/`outline_color`/`outline_alpha`, hollow
+shapes, `scale`, and segmentation boundaries via `contour_px`.
+:::
+
 ::::
 <!-- gallery-cards-end -->
 
@@ -66,4 +76,5 @@ color_and_palette
 multi_panel_color
 performance
 scalebars
+styling_shapes_and_labels
 ```