Add vitest coverage for router, pages, and tool renderers #167

Job	Run time
mypy	23s
Verify prod requirements.txt is sufficient	10s
Frontend unit tests (vitest) (ubuntu-latest)	20s
pytest (windows-latest)	1m 33s
API integration tests + coverage (macos-latest)	33s
ruff + pip-audit (ubuntu-latest)	25s
ruff + pip-audit (windows-latest)	1m 6s
API integration tests + coverage (ubuntu-latest)	17s
Frontend unit tests (vitest) (macos-latest)	36s
Performance benchmarks (informational)	29s
API integration tests + coverage (windows-latest)	58s
ruff + pip-audit (macos-latest)	19s
pytest (ubuntu-latest)	43s
pytest (macos-latest)	27s
Frontend unit tests (vitest) (windows-latest)	1m 13s
	9m 32s

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