✨ [RUM-14340] attach sdk version to events

[bcaudan]

Motivation

The SDK sends telemetry events with a hardcoded version: '0.0.0'. This attaches the real SDK version from package.json to telemetry events.

Changes

• Inject __SDK_VERSION__ build-time constant via @rollup/plugin-replace
• Replace hardcoded version: '0.0.0' in telemetry context with __SDK_VERSION__
• Add define entry in vitest config for unit test support
• Assert SDK version in E2E telemetry and view scenarios
• Document build-time constants pattern in DEVELOPMENT.md

Test instructions

• Run the playground app and generate telemetry errors / RUM events
• Verify in the Datadog app that sdk_version is correctly set on received events

Checklist

• Tested locally (playground)
• Added unit tests for this change.
• Added e2e/integration tests for this change.
• Updated related documentation.