refactor: Move `ui.Theme.from_brand()` Sass code into an `.scss` file #6072

Job	Run time
check (3.12, ubuntu-latest)	2m 43s
check (3.12, windows-latest)	6m 20s
check (3.12, macOS-latest)	1m 55s
check (3.11, ubuntu-latest)	2m 26s
check (3.11, windows-latest)	6m 11s
check (3.11, macOS-latest)	1m 53s
playwright-deploys-precheck (3.10)	1m 27s
check (3.10, ubuntu-latest)	2m 34s
check (3.10, windows-latest)	6m 43s
check (3.10, macOS-latest)	1m 59s
check (3.9, ubuntu-latest)	2m 34s
check (3.9, windows-latest)	5m 18s
check (3.9, macOS-latest)	2m 5s
playwright-examples (3.12, chromium)	3m 58s
playwright-examples (3.12, firefox)	4m 37s
playwright-examples (3.12, webkit)	3m 50s
playwright-examples (3.11, chromium)	3m 43s
playwright-shiny (3.12, chromium)	4m 52s
playwright-examples (3.11, firefox)	4m 23s
playwright-shiny (3.12, firefox)	5m 59s
playwright-examples (3.11, webkit)	3m 33s
playwright-shiny (3.12, webkit)	4m 38s
playwright-examples (3.10, chromium)	3m 53s
playwright-shiny (3.11, chromium)	4m 43s
test-narwhals-integration	44s
playwright-examples (3.10, firefox)	4m 30s
playwright-shiny (3.11, firefox)	5m 8s
playwright-examples (3.10, webkit)	4m 15s
playwright-shiny (3.11, webkit)	4m 56s
playwright-examples (3.9, chromium)	4m 16s
playwright-shiny (3.10, chromium)	5m 26s
playwright-examples (3.9, firefox)	4m 18s
playwright-shiny (3.10, firefox)	6m 22s
playwright-examples (3.9, webkit)	3m 56s
playwright-shiny (3.10, webkit)	4m 47s
playwright-shiny (3.9, chromium)	5m 36s
playwright-shiny (3.9, firefox)	5m 5s
Deploy to PyPI	0s
	2h 31m 36s

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