WEBDEV-7768 Search beta: Tile box shadow customization & smart facet adjustments

[latonv]

Two changes in preparation for the new search beta:

• Box shadows on tiles are currently always dark and thick. To allow more flexibility in how tiles are displayed in various contexts, this PR exposes two CSS vars that allow them to be customized more easily.
• The smart facets regain a text label, which is now customizable from outside the component.
• Clicking the default label of a smart facet dropdown now selects it immediately, rather than opening the dropdown menu (consistent with how the sort bar dropdowns function). Dropdown menus can still be opened by clicking the arrow.

[github-actions]

PR Preview Action v1.6.2
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2025-09-29 16:19 UTC

[codecov]

Codecov Report

❌ Patch coverage is 30.06993% with 100 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.64%. Comparing base (39349b1) to head (11be115).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
.../collection-facets/smart-facets/smart-facet-bar.ts	15.30%	83 Missing ⚠️
...ection-facets/smart-facets/smart-facet-dropdown.ts	53.84%	12 Missing ⚠️
src/collection-browser.ts	70.58%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #497      +/-   ##
==========================================
- Coverage   92.98%   92.64%   -0.34%     
==========================================
  Files         112      112              
  Lines       18537    18641     +104     
  Branches     1455     1456       +1     
==========================================
+ Hits        17236    17270      +34     
- Misses       1230     1300      +70     
  Partials       71       71              

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[bfalling]

LGTM