refactor(ui): share cross-platform visual semantics

[richardsolomou]

Problem

Desktop and mobile duplicate the same application palette, so editor, terminal, confetti, and native rendering can drift. Mobile also maps pull-request lifecycle states independently from the existing core presentation policy.

Changes

Move the application palette and brand colors into @posthog/shared, then consume those tokens from mobile and desktop rendering. Mobile's PR badge now uses the core PR visual policy while retaining its native component and icons.

How did you test this?

• Monorepo typecheck
• Shared suite: 738 tests
• Mobile suite: 501 tests
• UI suite: 2,351 tests
• Biome and host-boundary checks

Automatic notifications

• Publish to changelog?
• Alert Sales and Marketing teams?

---

Created with PostHog Code

[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit 54610e6.}

[trunk-io]

✨ Submitted to Merge by @richardsolomou. It will be added to the merge queue once all branch protection rules pass and there are no merge conflicts with the target branch. See more details here.

[greptile-apps]

_{Reviews (1): Last reviewed commit: "Merge main into cross-platform visual se..." | Re-trigger Greptile}

[charlesvien]

Hey @richardsolomou, we've migrated this repo into the PostHog/posthog monorepo, so this PR needs to be recreated there.

Easiest path: check out the monorepo and run the /porting-code-prs skill with your agent pointed at this PR. It has the migration guide and path remappings baked in so the agent doesn't have to figure them out. You don't strictly need it though, just asking your agent to port the PR works fine too.

Shout if you get stuck.