fix: declare wolframalpha as a project dependency

[obchain]

What

Add wolframalpha>=5.0.0 to pyproject.toml [project].dependencies and requirements.txt.

Why

src/opendeepsearch/wolfram_tool.py:2 does:

import wolframalpha

but wolframalpha is not declared as a project dependency and is not pulled in transitively. The README's "ReAct agent with math and search tools" example (around WolframAlphaTool(app_id=...)) is the headline use case for this module, so following the README out of the box fails with:

ModuleNotFoundError: No module named 'wolframalpha'

before any agent step runs.

Fixes #57

How

• pyproject.toml: append "wolframalpha>=5.0.0" to the inline dependencies = [...] array (keeping the existing single-line style)
• requirements.txt: add wolframalpha>=5.0.0 next to the other tool-side packages (smolagents, gradio, wikipedia-api)

5.0.0 is the current stable line on PyPI and the API surface WolframAlphaTool uses (Client(app_id).query(...).pods[*].subpods[*].plaintext) has been stable across the 5.x series.

I did not move wolframalpha to a [project.optional-dependencies] extra. The README treats it as a first-class example without any pip install opendeepsearch[wolfram] step, and the other tool-side packages (smolagents, gradio, wikipedia-api) are declared as base deps for the same reason. Happy to refactor into an extra if you'd prefer.

Testing

• python3 -c "import tomllib; assert 'wolframalpha>=5.0.0' in tomllib.loads(open('pyproject.toml','rb').read().decode())['project']['dependencies']" — pass
• grep -n wolframalpha requirements.txt — wolframalpha>=5.0.0
• After uv pip install -e . on a clean venv, python -c "from opendeepsearch.wolfram_tool import WolframAlphaTool; print(WolframAlphaTool)" succeeds where it previously raised ModuleNotFoundError.