docs(lab): codify immutable laboratory runs

docs/09_OBSERVATION_SESSIONS.md

@@ -481,7 +481,8 @@ policy.
 All paths are same-origin and expose opaque identifiers only:
 
 ```text
-GET  /api/v1/observation-sessions?limit=3
+GET  /api/v1/observation-sessions?limit=3&scope=source
+GET  /api/v1/observation-sessions?limit=3&scope=laboratory
 GET  /api/v1/observation-sessions/{id}
 POST /api/v1/observation-sessions/{id}/replay
 GET  /api/v1/observation-sessions/{id}/recording-preparation
@@ -498,6 +499,11 @@ PUT  /api/v1/workspace-layouts/observation.spatial
 ```
 
 The catalog embeds each replayable session's preparation state and progress.
+`scope=source` returns only original physical records and is the only scope
+used by **Данные → Сессии и записи**. `scope=laboratory` returns immutable LAB
+projections. `scope=all` is reserved for internal joins such as resolving a LAB
+projection together with its source; pagination is applied after the scope
+filter so a growing LAB history cannot hide original records.
 `POST .../replay` returns either a verified replay v2 launch document or HTTP
 202 with the preparation v1 document, `Location`, `Retry-After`, an exact quoted
 preparation `ETag` and a same-origin status URL. Polling