docs(adaptyv): standardize on ADAPTYV_API_KEY across examples

[mvanhorn]

Fixes #182.

scientific-skills/adaptyv/SKILL.md told code to read the API key from ADAPTYV_API_KEY (line 17), but two examples disagreed:

• The curl example exported FOUNDRY_API_TOKEN and used $FOUNDRY_API_TOKEN in the Authorization header.
• The Python "Client Pattern" example constructed FoundryClient(api_key="...", ...) with a hardcoded literal placeholder, contradicting the env-var guidance.

This PR makes both examples use ADAPTYV_API_KEY directly:

• The bash block now exports and references ADAPTYV_API_KEY.
• The Python client snippet reads api_key from os.environ["ADAPTYV_API_KEY"] and falls back the base URL through os.environ.get("ADAPTYV_API_URL", "https://foundry-api-public.adaptyvbio.com/api/v1"), matching the "Environment variables" block above it.

Pure docs change. No code changes.

AI was used for assistance.

[mvanhorn]

The Scan changed skills check is failing with Process completed with exit code 1 but the GitHub annotations don't expose the actual scanner output. I couldn't reproduce locally - PyPI access is blocked in my sandbox so I can't install the scanner dependencies. Could you share the scan log output (or rerun the workflow with debug logging)? I tried a guess at standardizing further on ADAPTYV_API_KEY but reverted it since it expanded scope beyond the original PR. Happy to apply a targeted fix once I can see what the scanner is rejecting.