Credentials UI: leftover host wording and narrow-list

Found while visually checking Task 6753 on Credentials (list + Add/Edit form). Suggestions: 1. `testers.py::_host_advice` still says "check the base URL." for every operator-chosen host, so a Make/Headscale/Generic API Key unexpected-body or transport failure names a field the form doesn't show ("Zone URL", "API URL"). Name the type's own host field label, as the OIDC tester already does. 2. Beside an open editor the list is ~550px and the Type column's 32cqw cap ellipsises "GitHub OAuth App (connect and…"; consider a shorter list label for the connect-flow types (e.g. "GitHub OAuth App") or wrapping only in the beside-detail layout. 3. At 1024px the filter strip wraps with a lone "Secrets" select and "Only mine" on a second row; beside an open editor the Tree/Flat toggle sits alone on a third row. Pack the strip so controls don't strand on their own rows. Out of scope: credential types, testers' verdict logic, sealing/host-pin rules. Done means: - Each failure sentence names the type's own host-field label (API unit test). - Screenshots at 1024px and beside an open editor show no stranded filter controls and readable type labels.

Host advice now names each type's own field label (per-type API test); short Type label beside the editor; filter strip packs with no stranded controls (checked on screenshots). PR #5688 merged. Only gate failure: a packaging selftest that passes on its own. Follow-up: draft 6868.