feat(mobile-help): add in-app user guide

[Adamskiee]

Summary

Adds a post-onboarding SAPOT mobile guide with a versioned spotlight tour and persistent offline Help Center.

• Adds typed, role- and mode-filtered help articles and article routes.
• Persists tour completion through secure storage, with a fail-closed autostart gate and replay support.
• Adds the tour provider, anchors, overlay, and Help affordances in the drawer, tabs, announcements, and peer profile.
• Documents the feature and secure-storage key.

Validation

• pnpm run testAll
• pnpm run typecheck
• pnpm run lint
• pnpm test -- --runInBand features/help

Manual smoke test

Open Settings > Support > Help Center, read an article, then choose Take the tour again and return Home.