add/fix(langfuse): log levels

[Hansehart]

Related Issues

• fixes Langfuse Integration: add support for log levels #1265

Proposed Changes:

Replaced the try/finally pattern with a try/except/else pattern that properly captures and propagates exception information.
The Langfuse tracer was always calling exit(None, None, None) in a finally block, regardless of whether an exception occurred during pipeline execution. This told Langfuse/OpenTelemetry that all operations completed successfully, even when exceptions were raised.

How did you test it?

unit tests, manual verification

Notes for the reviewer

• Errors are now automatically displayed in Langfuse. Before it looked like success. Warnings and Debug messages can be set manually.
• Some formatting happend from hatch run fmt

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.

[Hansehart]

[vblagoje]

thanks @Hansehart - I'll take a look @sjrl

[vblagoje]

Looks mostly good but it seems we have some minor DRY violations where we can have one finally block (for try/else) with flush and token reset. wdyt?

[Hansehart]

@vblagoje You're absolutely right! I have to admit its hard to read. But now its a bit better.

[vblagoje]

LG