Make landing statistics link to relevant views

[realmarcin]

Summary:

• Turn all landing-page statistic panels into keyboard-accessible links.
• Route the community total and category count to the browser and category facets.
• Route the embedding statistic to the UMAP view.
• Regenerate the published landing page and add a regression test.

Validation:

• just qc: 2,853 passed, 98 skipped, 8 deselected; all record, strict-schema, GTDB, and scalar gates passed
• just check-docs-current
• git diff --check

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