Add vitest coverage for router, pages, and tool renderers #165

Job	Run time
Performance benchmarks (informational)	27s
Frontend unit tests (vitest) (ubuntu-latest)	22s
API integration tests + coverage (ubuntu-latest)	22s
API integration tests + coverage (macos-latest)	16s
Frontend unit tests (vitest) (macos-latest)	26s
Verify prod requirements.txt is sufficient	7s
Frontend unit tests (vitest) (windows-latest)	42s
ruff + pip-audit (ubuntu-latest)	23s
pytest (ubuntu-latest)	42s
mypy	23s
pytest (macos-latest)	39s
ruff + pip-audit (macos-latest)	18s
pytest (windows-latest)	1m 16s
API integration tests + coverage (windows-latest)	1m 10s
ruff + pip-audit (windows-latest)	1m 5s
	8m 38s

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