profile: add gated public profile controls

[jamesacklin]

Summary

This PR adds public profile controls to the profile editor and wires them to %profile via pokes/scries. It also gates those controls behind a Tlon-only experimental feature flag.

Changes

• Added packages/shared/src/api/profileApi.ts and exported it from packages/shared/src/api/index.ts.
• Implemented public profile controls in packages/app/ui/components/EditProfileScreenView.tsx:
  • Toggle public /profile on/off (start/suspend %profile, bind/unbind route).
  • Toggle widgets for Profile info, Bio, Featured posts, and Message me.
  • Load current bound/layout state on screen load and reconcile UI state from layout.
• Added publicProfileControls feature flag in packages/app/lib/featureFlags.ts (onlyTlon: true, default off).

How did I test?

• Flip the feature flag on if you are a Tlon employee

• Visit the profile editor

• Enable your public profile

• Visit https://your-ship-url.com/profile

• Confirm you see a page

• Disable the public profile

• Visit https://your-ship-url.com/profile

• Confirm the page redirects

• Re-enable the public profile

• Flip various sections on and off

• Refresh the public profile page

• Confirm you see the sections appear and disappear

Risks and impact

• Safe to rollback without consulting PR author? Yes
• Affects important code area:
  • Onboarding
  • State / providers
  • Message sync
  • Channel display
  • Notifications
  • Other: Profile settings UI and %profile poke/scry integration

Rollback plan

• Revert this PR.
• Confirm EditProfileScreenView no longer renders public profile controls.
• Confirm packages/shared/src/api/profileApi.ts exports/usages are removed by revert.

Screenshots / videos