fix(connections): make automatic relay route removal controls consistent #360

What: Route controls must explain that account-discovered relay routes are learned again.
Why: The #292 account watcher will restore a removed relay while the account still advertises a usable tunnel.
So what: Track this bounded follow-up separately from #292's automatic relay-learning implementation, per the user's round-2 review rule.

Outcome

Choose and implement the smallest consistent remove/re-add behavior for automatic relay routes across web, desktop and mobile.

Acceptance

Removing a route must not report a durable removal that reconciliation immediately reverses; supported ways to stop automatic membership are clear and tested.

Evidence

Current web EnvironmentRoutesList.tsx and mobile features/settings/EnvironmentRoutesSection.tsx permit relay removal, unlike learned direct routes.
Source base: 503282b. Design record: #292 (comment).

Non-goals and blockers

No tunnel creation, authentication changes or primary-environment routing.
No implementation is assigned in this task. The retained-last-route lifecycle needs a product decision before destructive behavior is selected.

Contribution to the Objective

Reliable remote route state keeps the Promachos and Drafters reachable across machines.

Requirements and who asked: The user's #292 review instruction requires non-core findings from round 2 onward to become linked follow-up Issues.
Deleted: Expanding the current automatic membership fix with this separate behavior.
Bottleneck: Choose and implement the smallest consistent remove/re-add behavior for automatic relay routes across web, desktop and mobile.
Checked myself: Current web EnvironmentRoutesList.tsx and mobile features/settings/EnvironmentRoutesSection.tsx permit relay removal, unlike learned direct routes.