Refresh doc links for docs v2.0

Following the docs v2.0 release, every doc link across the dashboard, marketing site, and docs site has been audited and pointed at the current pages so users land on the right place instead of a stale route.

• Repointed dashboard empty states, deployment pages, and OpenAPI references to the new docs IA.
• Updated landing footer, navbar, connector, and self-hosting links so the site sends visitors to the right docs.
• Fixed internal docs redirects after the data-model rename and refreshed SDK readmes with the new per-language guide links.