docs(report): add section 5.3 draft assets

docs/temp-section-5-3-diagrams/5.3.6-stream-sessions-and-signalling.md

@@ -0,0 +1,46 @@
+# 5.3.6 Stream Sessions and Signalling
+
+## Stream Request and WebRTC Signalling Sequence
+
+```mermaid
+sequenceDiagram
+    autonumber
+    participant Client as Client Browser
+    participant Backend as Backend /streams
+    participant Links as device_links
+    participant Session as stream_sessions
+    participant Camera as Camera Browser
+    participant RT as Socket.IO Relay
+
+    Client->>Backend: POST /streams/request
+    Backend->>Links: verify active camera-client link
+    Backend->>Session: insert requested session
+    Backend->>Camera: emit stream:requested
+    Camera->>Backend: POST /streams/:id/accept
+    Backend->>Session: update status to streaming
+    Backend->>Client: emit stream:started
+    Camera->>RT: webrtc:signal offer
+    RT->>Client: relay offer
+    Client->>RT: webrtc:signal answer
+    RT->>Camera: relay answer
+    Client->>RT: ICE candidates
+    RT->>Camera: relay ICE candidates
+    Camera->>RT: ICE candidates
+    RT->>Client: relay ICE candidates
+```
+
+## Stream Session State Diagram
+
+```mermaid
+stateDiagram-v2
+    [*] --> requested
+    requested --> streaming: camera accepts
+    requested --> cancelled: requester cancels
+    requested --> failed: validation or delivery failure
+    streaming --> completed: normal end
+    streaming --> cancelled: manual stop
+    streaming --> failed: connection or upload failure
+    completed --> [*]
+    cancelled --> [*]
+    failed --> [*]
+```