Issue-list sort defaults and server ranking preservation

Client-side sorting is only for multi-project issue results. Never apply getComparator('recommended') to a single-project result: it falls back to lastSeen ordering and would silently overwrite the server’s relevance ranking. Tests must also omit the sort flag and verify that the resolved default reaches the API: recommended for SaaS and date for self-hosted. Existing tests that always pass sort explicitly do not cover this integration behavior.