feat(ui): Add routing-only hostnames to the domain form

[nfebe]

A domain can now carry hostnames that route to the deployment but are never issued a certificate, for a hostname whose TLS is terminated by an external proxy such as Cloudflare. They are entered separately from ordinary aliases, which continue to request certificates, so the two cases are not confused.

Pairs with the agent-side routing support: flatrun/agent#177.

[sourceant]

Code Review Summary

This PR adds support for routing-only hostnames to the Domain configuration UI. This allows users to specify hostnames that route to a deployment without triggering certificate issuance, typically used when TLS is handled by an external provider like Cloudflare.

🚀 Key Improvements

• Added route_only_aliases to the DomainConfig type definition in src/types/index.ts.
• Updated DomainFormModal.vue with a dedicated form section for these hostnames, including management logic.
• Implemented unit tests in DomainFormModal.test.ts to ensure data is correctly hydrated into the form and emitted on save.

💡 Minor Suggestions

• Add aria-label to the removal buttons for better accessibility.
• Consider consolidating the alias management logic if more variations are added later.

[sourceant]

Review complete. See the overview comment for a summary.

[sourceant]

The remove button lacks an accessible label. Since it only contains an icon, screen readers won't be able to describe the action to users.

Suggested change

	<button type="button" class="remove-btn" @click="removeRouteOnly(index)">
	<button type="button" class="remove-btn" @click="removeRouteOnly(index)" aria-label="Remove hostname">
	<i class="pi pi-times" />
	</button>