UUID for each sandbox event

[sitole]

Insert and query the UUID for each sandbox event. Clickhouse migration to add fields to all existing events.

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Note

Add a UUID id to sandbox events and propagate it through schema, models, queries, insert batching, and event emission; remove unused product usage insert batcher.

• ClickHouse schema:
  • Add id UUID DEFAULT generateUUIDv4() to sandbox_events_local and sandbox_events (with down migration to drop it).
• Data models & queries:
  • Add id to clickhouse.SandboxEvent and shared/events.SandboxEvent.
  • Include id in SELECT queries in packages/clickhouse/pkg/sandbox_events.go.
• Ingestion/batching:
  • Update InsertSandboxEventQuery to write id; append event.ID in batcher.
• Event production:
  • Generate uuid.New() for each emitted sandbox event in server handlers and pass through SandboxEventsService to ClickHouse.
• Cleanup:
  • Remove product_usage_insert_batcher implementation.

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