fix(desktop): edit managed instance from agent profile

[camelludo]

Summary

• route agent-profile Edit to the concrete managed-instance editor when a managed record exists
• preserve persona-definition editing for profiles without a managed instance
• prevent edits to built-in persona defaults from silently missing runtime/subscription settings

Verification

• pnpm typecheck
• pnpm exec biome check src/features/profile/ui/UserProfilePanel.tsx
• pnpm exec node --import ./test-loader.mjs --experimental-strip-types --test src/features/agents/ui/agentDialogRouting.test.mjs src/features/profile/ui/UserProfilePanelPersonaSubmit.test.mjs

Scope

This is an upstream-compatible desktop UI fix. It does not alter relay configuration, identities, memberships, providers, or production services.

[camelludo]

Superseded by clean draft PR #5105. This draft was based on the lifecycle branch and therefore included unrelated workflow/runtime commits; #5105 is based directly on upstream main and contains only the managed-instance profile routing fix.