Part of Extra-Chill/extrachill-admin-tools#16.

Scope

Take ownership of the user-domain capabilities currently registered by extrachill-admin-tools:

• extrachill/sync-team-members
• extrachill/manage-team-member
• extrachill/grant-lifetime-membership
• extrachill/revoke-lifetime-membership
• Artist access request administration and destination links

Move business logic beneath REST/ability adapters rather than invoking REST callbacks from abilities. Preserve ability names, input schemas, output shapes, and intentional CLI/automation permissions unless a security correction is explicitly documented and tested. Add focused owner-native network admin screens only where the UI remains useful; do not recreate the mixed Admin Tools umbrella.

Acceptance criteria

• User-domain abilities are registered by this plugin and covered by tests.
• Existing team role primitives remain the source of truth.
• Lifetime membership logic no longer depends on an Admin Tools wrapper.
• Artist access email/admin links target a valid owner-native network admin screen.
• Migration supports a rollout with no duplicate ability registration.
• Relevant REST consumers retain compatible behavior.
• Lint and focused tests pass.

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