refactor(APP-1338): Move the ChangeMembers action view to the app and drop the kit's built-in action views

[milosh86]

Description

Moves the last gov-ui-kit proposal action view, ChangeMembers, into the app, and removes the kit's built-in action-view machinery now that nothing is left behind it. Follows #1433 (WithdrawToken), #1489 (UpdateMetadata), #1492 (TokenMint) and #1493 (ChangeSettings).

Stacked on #1493: this PR targets app-1339-migrate-changesettings-action. Change the base to main once #1493 (and #1492 below it) are merged (GitHub does it automatically if those branches are deleted on merge).

App

• New MultisigChangeMembersActionDetails in apps/app/src/actions/multisig/, registered in the action view registry for MultisigAddMembers and MultisigRemoveMembers through initMultisigActionViews. It renders a member item per added or removed member (ENS name when available, block-explorer link through useDaoChain), plus the added/removed count, the existing member count and the block note. Copy moved to app.actions.multisig.multisigChangeMembersActionDetails.*.
• The view reads the multisig action directly, because members and currentMembers already come from the backend. Removed multisigActionUtils.normalizeChangeMembersAction / isChangeMembersAction and their branch in useMultisigNormalizeActions, which only renamed the type to the kit's ADD_MEMBERS / REMOVE_MEMBERS.
• IMultisigActionChangeMembers now extends the app's IProposalAction instead of the kit type. New generateMultisigActionChangeMembers test generator.
• Cross-chain forwarded member changes keep rendering as raw calldata, as before.

gov-ui-kit (breaking, major changeset)

• Removed ProposalActionChangeMembers, IProposalActionChangeMembers / IProposalActionChangeMembersProps, generateProposalActionChangeMembers and the proposalActionChangeMembers modules copy.
• Final cleanup, since no built-in action views remain: removed the proposalActionsList module, ProposalActionsItemBasicView, proposalActionsItemUtils (isActionSupported, isChangeMembersAction) and the now-empty ProposalActionType enum. ProposalActions.Item renders CustomComponent directly as its BASIC view. Without one, the BASIC view mode is disabled and the item opens the decoded or raw view. ProposalActionTypeNoBasicView stays exported.
• The ProposalActions.Item "Native" story is replaced by a "CustomView" story that passes a CustomComponent. The ProposalActions.Root stories use generic decoded actions.
• Updated the ProposalActions usage notes and comments, and regenerated the component registry and selection guide.

Tests

• Ported the kit ChangeMembers tests (existing members, added, removed, block note, block-explorer links) and added cases for the deleted stories: ENS-named members next to plain addresses, for both adding and removing. Also added an empty-members case. They render the real member item, so names, truncated addresses and links are checked in the DOM.
• The kit basic-view and utils tests moved into ProposalActions.Item tests: CustomComponent receives the action, index, chain id and web3 props, the BASIC view is disabled without it, and the tests that faked isActionSupported now pass a real CustomComponent.
• useMultisigNormalizeActions now asserts members actions pass through unchanged.
• Checked every story removed across the five migrations against the app tests. The ChangeSettings story (three settings, one unchanged) had no matching test, so this PR adds one.

Changesets: @aragon/gov-ui-kit major and @aragon/app patch, one changeset per release scope.

Type of Change

• Major: Breaking change (change that would cause existing functionality to not work as expected)
• Patch: Enhancement (non-breaking change to an existing feature)

Developer Checklist:

• Manually smoke tested the functionality in a preview or locally
• Confirmed there are no new warnings or errors in the browser console
• (For User Stories only) Double-checked that all Acceptance Criteria are satisfied
• Confirmed there are no new warnings on automated tests
• Merged and published any dependent changes in downstream modules
• Selected the correct base branch
• Commented the code in hard-to-understand areas
• Followed the code style guidelines of this project
• Reviewed that the Files Changed in Github’s UI reflect my intended changes
• Confirmed the pipeline checks are not failing

Review Checklist:

• (For User Stories only) Tested in a preview or locally that all Acceptance Criteria are satisfied
• Confirmed that changes follow the code style guidelines of this project

[linear-code]

APP-1338

[github-actions]

🚀 Preview Deployment: View Here

[github-actions]

E2E results (preview)

Smoke

Base URL	https://app-next-399n8lxk9-aragon-app.vercel.app
Suite	smoke
Playwright result	✅ passed
Summary	86 passed
HTML report	View report
GitHub job	✅ completed

View run #5558

[thekidnamedkd]

LGTM 🛶