feat(loops): surface loop ownership and notifications

[MattPua]

Problem

Loop lists and details hide notification channels and ownership, and personal and team loops are mixed together.

Changes

Before:

After:

• Split personal and team loops into separate sections
• Show notification channels and creator attribution in list rows and details
• Handle creator loading, missing-member, and lookup-error states

How did you test this?

• pnpm --filter @posthog/ui typecheck
• pnpm --dir packages/ui exec vitest run src/features/loops/loopDisplay.test.ts src/features/canvas/utils/mentionComposer.test.ts
• pnpm exec biome check on changed files

Automatic notifications

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

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Created with PostHog Code

[trunk-io]

😎 This pull request was merged.

[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit f1b2b5e.}

[posthog]

✅ Visual changes approved by @MattPua — baseline updated in 9c0efc5.

View this run in PostHog

4 new.

[greptile-apps]

Prompt To Fix All With AI

Fix the following 2 code review issues. Work through them one at a time, proposing concise fixes.

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### Issue 1 of 2
packages/ui/src/features/loops/components/LoopsListView.tsx:67
**Members Cache Crosses Organizations**

`useOrgMembers` uses the shared `['org-members']` cache key, so switching organizations can leave this new creator lookup reading the previous organization's members during the stale window. Team loops can then show another user's name when numeric IDs overlap, or incorrectly label a current creator as a former member.

### Issue 2 of 2
packages/ui/src/features/loops/components/LoopDetailView.tsx:264-265
**Partial Results Imply Former Member**

The organization-members request stops after 20 pages and returns the members loaded so far. In an organization with more than 4,000 members, a current creator on a later page is absent from `members`, so this branch incorrectly displays “Former organization member.”

_{Reviews (1): Last reviewed commit: "chore(visual): update storybook baseline..." | Re-trigger Greptile}