Preserve imported service endpoints

[davejohnson]

What changed

• Preserve each imported service's public URL and custom domains in the generic HostingBindings record.
• Resolve hv_health through the environment's declared domain when a web service has no provider URL binding.
• Parse health bindings through the provider-neutral hosting binding schema.
• Add Railway import regression coverage and Cloud Run-shaped coverage for declared-domain health resolution.

Root cause

Railway inspection collected per-environment service domains, but importRailwayProject persisted only the service ID. As a result, a freshly adopted service appeared healthy in live observation while repo-backed hv_health service=web failed with no URL binding.

The health fallback was also binding-only even when the desired-state spec already declared the public domain.

Impact

Fresh adoption now produces reconstructible endpoint bindings. Health checks can also use a declared web domain consistently across hosting providers; Railway remains the current import source, but the stored shape and health behavior are provider-neutral.

Validation

• vitest run --configLoader runner: 108 files, 885 tests passed
• tsc --noEmit
• npm run build
• Re-adopted Invoice Perfect staging and verified hv_health service=web returns HTTP 200 without an explicit URL