Integrate Langfuse for llm observability

[schobele]

This pull request introduces several changes to integrate OpenTelemetry for enhanced observability and telemetry, refactor imports for better organization, and add new utility functions. The most important changes are summarized below:

Integration of langfuse

• Added dependencies for OpenTelemetry and Langfuse in package.json.
• Updated src/ai/openai.ts to configure and start the OpenTelemetry SDK with Langfuse exporter.
• Enabled experimental telemetry in various aisdk calls across multiple files to collect trace data. [1] [2] [3]

Added langfuse observability features to BaseAssistant Class

• Modified the BaseAssistant class in src/ai/Assistant.ts to include tracing capabilities and optional run context parameters. [1] [2]

Miscellaneous Changes

• Added initialization for Langfuse in src/langfuse/index.ts.
• Ensured the OpenTelemetry SDK starts in the main application entry point src/index.ts.