fix: Fix regressions after Material 3 migration

[g123k]

Hi everyone!

This PR fixes three things:

• The white-on-white button in dark mode (@see Dark mode issue #5738)
• The same buttons now have a bolder font
• Add a shadow to the BottomNavigationBar

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 22 lines in your changes missing coverage. Please review.

Project coverage is 6.96%. Comparing base (4d9c7fc) to head (3dc33a0).
Report is 394 commits behind head on develop.

Files with missing lines	Patch %	Lines
packages/smooth_app/lib/pages/page_manager.dart	0.00%	19 Missing ⚠️
...ackages/smooth_app/lib/pages/scan/scan_header.dart	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           develop   #5740      +/-   ##
==========================================
- Coverage     9.54%   6.96%   -2.58%     
==========================================
  Files          325     407      +82     
  Lines        16411   21782    +5371     
==========================================
- Hits          1567    1518      -49     
- Misses       14844   20264    +5420     

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[teolemon]

Thanks for the speedy fix @g123k 👌