offline navigations: add docs and examples (10/10)

[feedthejim]

Stack Position

This is PR 10 of 10. It adds the user-facing docs and examples for experimental.offlineNavigations.

Review guide:
https://gist.github.com/feedthejim/a10f757cf07c5550f731adf2fcf1077b

Full Stack

1. offline navigations: add gated build primitives (1/10) #93736 offline navigations: add gated build primitives (1/10)
2. offline navigations: generate fallback document artifacts (2/10) #93737 offline navigations: generate fallback document artifacts (2/10)
3. offline navigations: register pass-through worker (3/10) #93625 offline navigations: register pass-through worker (3/10)
4. offline navigations: cache fallback and current-build assets (4/10) #93626 offline navigations: cache fallback and current-build assets (4/10)
5. offline navigations: serve fallback document offline (5/10) #93627 offline navigations: serve fallback document offline (5/10)
6. offline navigations: add router-cache persistence primitives (6/10) #93630 offline navigations: add router-cache persistence primitives (6/10)
7. offline navigations: persist cached router records (7/10) #93640 offline navigations: persist cached router records (7/10)
8. offline navigations: bootstrap fallback from router records (8/10) #93644 offline navigations: bootstrap fallback from router records (8/10)
9. offline navigations: support dynamic route patterns (9/10) #93647 offline navigations: support dynamic route patterns (9/10)
10. This PR: offline navigations: add docs and examples (10/10) #93738 offline navigations: add docs and examples (10/10)

What This Changes

This adds documentation for the first usable offline navigation scope:

• the experimental.offlineNavigations config option;
• the cacheComponents requirement;
• the relationship to useOffline;
• what users should perceive when they go offline;
• how normal Link viewport prefetching makes a route available for offline hard reload;
• what framework assets and router records are cached;
• what is intentionally not guaranteed yet;
• how existing router refresh and server invalidation APIs keep the offline copy from outliving the regular router cache.

What Works After This PR

Reviewers and early users have a guide, API reference, and cross-links that describe the same behavior implemented by PRs 1-9.

What Does Not Work Yet

This does not document a stable API. The feature remains experimental and Cache Components only. Dev simulation, custom offline miss UI, output export integration, and broader lifecycle controls remain follow-up work.

Reviewer Focus

Please focus on whether the docs explain the user-facing contract without over-documenting implementation details, and whether the caveats are practical for production apps rather than demo-only.

Proof in This PR

Docs lint passed for the edited docs:

• npx eslint --config eslint.config.mjs docs/01-app/02-guides/offline-navigations.mdx docs/01-app/03-api-reference/05-config/01-next-config-js/offlineNavigations.mdx

The full stack behavior referenced by the docs is covered by:

• HEADLESS=true pnpm test-start-turbo test/e2e/app-dir/offline-navigations-deploy/offline-navigations-deploy.test.ts
• HEADLESS=true pnpm test-start-turbo test/production/app-dir/offline-navigations/offline-navigations.test.ts
• HEADLESS=true pnpm test-start-webpack test/production/app-dir/offline-navigations/offline-navigations.test.ts

Deferred Coverage

True deploy-mode proof is pending CI or a custom deploy run because the local test-deploy-turbo attempt timed out during vercel link.

Docs Status

This PR is the docs slice for the stack.

[github-actions]

Tests Passed

Commit: 3867a97