The dashboard's unread-comment-threads flow fired one
get-profiles-for-file-comments RPC call per file-id, producing
20+ concurrent HTTP requests and 20+ SQL queries for users with
unread threads across multiple files.
Widen the existing get-profiles-for-file-comments RPC to accept a
set of file ids (max 100) instead of a single id. The SQL uses
ANY(?::uuid[]) so a 1-element set has the same query plan as the
previous file_id = ?. Update the frontend unread-threads flow to
send a single batch request, and the workspace fetch-profiles
event to wrap the current file id in a 1-element set. The 100 cap
is enforced in both the frontend (with a log/warn on overflow) and
the schema (:max 100).
Fixes#10587
AI-assisted-by: opencode-go/minimax-m3
