fix(pet): each user's pet tells only of their own sessions

An admin/analyst's pet counted every user's sessions (live, waiting, errors)
because their WebSocket carries everyone's. Server mode now marks their
session/agent/event frames `mine: true|false` (scope.broadcastAudience owners,
worked out once per broadcast), and GET /api/sessions?mine=1 lists only the
caller's own sessions (ownSessionWhere). The pet seeds from mine=1 and skips
frames marked mine: false. Developers and local mode are unchanged.

server/openapi-extra/override-sessions-agents.js

@@ -154,6 +154,14 @@ const paths = {
             "`1` = only sessions blocked on the user (`awaiting_input_since IS NOT NULL AND status = 'active'`), the UI's Waiting filter. Applied before `limit`/`offset`, so `total` stays exact.",
           example: "1",
         },
+        {
+          name: "mine",
+          in: "query",
+          schema: { type: "string", enum: ["1"] },
+          description:
+            "Server mode: `1` = only the caller's OWN sessions, even for an admin or analyst (the pet's count). No-op in local mode.",
+          example: "1",
+        },
         {
           name: "from",
           in: "query",