docs(experimentation): add experimentation architecture to platform architecture page

docs/docs/flagsmith-concepts/platform-architecture.md

@@ -18,6 +18,10 @@ The most important components in Flagsmith's architecture are:
 - **SDKs**: Client libraries (available for many languages and platforms) that connect your applications and services to Flagsmith, enabling real-time feature flag evaluation and remote configuration.
 - **Integrations**: Optional connectors to third-party tools and services (e.g., analytics, notifications, monitoring). These can be configured via the dashboard or API.
 - **Database**: Stores all persistent data, such as organisations, projects, features, and audit logs. Managed by Flagsmith in SaaS, but by your team in self-hosted/on-prem deployments.
+- **Ingestion server**: A web service that receives events from SDKs (e.g. for [experimentation](/experimentation)) and writes them to Kafka.
+- **Kafka**: Message bus used to reliably deliver events to the warehouse.
+- **Warehouse delivery**: Inserts events into each environment's warehouse, retries failed inserts, and records delivery status.
+- **Warehouse**: Analytical database that stores events and runs the aggregations the Core API requests.
 
 The architecture is REST-based, with both SDK clients and the dashboard interacting with the Core API. The platform is designed to be cloud-native, supporting containerisation and orchestration for scalability and reliability.
 
@@ -36,6 +40,14 @@ Flagsmith can be deployed in three main ways, each with conceptual differences i
 
 *The diagram above shows the SaaS deployment model, where all infrastructure is managed by Flagsmith and the Edge API ensures global low-latency delivery.*
 
+#### Experimentation on SaaS
+
+Flagsmith runs the whole experimentation pipeline. Events go to the Flagsmith-managed ClickHouse warehouse directly from Kafka, or to your own warehouse through warehouse delivery.
+
+![SaaS Experimentation Architecture](/img/experimentation-architecture-saas.svg)
+
+*The diagram above shows how experiment events flow on SaaS, to the managed warehouse or to your own.*
+
 ### 2. Self-Hosted (Cloud or Private Cloud)
 
 - **Managed by your team**: Deploy Flagsmith on your own cloud infrastructure (e.g., AWS, GCP, Azure, DigitalOcean) using Docker, Kubernetes, or other orchestration tools.
@@ -54,6 +66,14 @@ Flagsmith can be deployed in three main ways, each with conceptual differences i
 
 *The diagram above illustrates the Self-Hosted and On-Premises deployment models, where your team manages the infrastructure and has full control over security, compliance, and integrations.*
 
+#### Experimentation on Self-Hosted and On-Premises
+
+Your team runs the ingestion server, Kafka and warehouse delivery alongside the Core API. Events go to your own warehouse through warehouse delivery. See [Connect a Warehouse](/experimentation/connect-a-warehouse) for supported warehouses.
+
+![Self-Hosted Experimentation Architecture](/img/experimentation-architecture-self-hosted.svg)
+
+*The diagram above shows how experiment events flow on Self-Hosted and On-Premises deployments, where every component, including the warehouse, is run by your team.*
+
 ## What's next
 - [Deployment Options](/deployment-self-hosting)
 - [Version Comparison](https://flagsmith.com/pricing)