add LlamaIndex zero-code OTLP example

[mesutoezdil]

Closes #94

Adds a zero-code OTLP example for LlamaIndex. Follows the same pattern as the other examples in this directory.

What was added:

• run.py runs a LlamaIndex FunctionAgent with two tools and sends traces via OTLP
• requirements.txt lists the required packages

How to run:

pip install -r examples/zero-code-examples/llama-index/requirements.txt
agentevals serve --dev
export OPENAI_API_KEY=your-key
python examples/zero-code-examples/llama-index/run.py

Test:
Ran the script with an OpenAI-compatible endpoint (Qwen3-32B via OpenAI-compatible API).

Queries and results:

• "Hi! Can you help me?" got a response without calling any tool
• "Roll a 20-sided die." called roll_die(20) and returned the result
• "Roll a 6-sided die and check if the result is prime." called roll_die(6) then check_prime(result) and gave the correct answer

All three queries passed. Traces were flushed at the end.

@krisztianfekete