docs(report): add section 5.3 draft assets

docs/temp-section-5-3-diagrams/5.3.1-server-bootstrap.md

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+# 5.3.1 Server Bootstrap and Runtime Setup
+
+This diagram shows how the backend starts, mounts services, and becomes ready to handle API and realtime traffic.
+
+```mermaid
+sequenceDiagram
+    autonumber
+    participant Node as Node Runtime
+    participant Index as Backend/index.ts
+    participant App as Express App
+    participant Auth as Better Auth
+    participant Routes as Route Modules
+    participant MinIO as MinIO
+    participant RT as Socket.IO Gateway
+    participant Rec as Recordings Worker
+    participant Push as Push Worker
+
+    Node->>Index: start process
+    Index->>App: create express app
+    Index->>App: configure helmet + cors + JSON middleware
+    Index->>Auth: mount /api/auth/*
+    Index->>Routes: mount videos/admin/devices/links/streams/events/recordings/ops
+    Index->>MinIO: ensureMinioBucket()
+    MinIO-->>Index: bucket ready
+    Index->>RT: setupRealtimeGateway(server)
+    Index->>Rec: startRecordingsWorker()
+    Index->>Push: startPushWorker()
+    Index->>App: listen on configured port
+```