feat: add MCP executable path support

[samrusani]

Proposed change

Adds custom Chromium executable support to the MCP browser tools. ScraplingMCPServer now accepts a global executable_path, falls back to SCRAPLING_EXECUTABLE_PATH, and lets browser tool calls override it per request or session. The value is wired through to AsyncDynamicSession and AsyncStealthySession, and the scrapling mcp command exposes --executable-path so MCP users can configure it once.

The MCP docs and API reference now show the server-wide configuration path.

Type of change:

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests
• Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
• Documentation change?

Additional information

• This PR fixes or closes an issue: fixes Allow specifying a custom Chromium browser #347
• This follows the issue thread's MCP-only plumbing direction; DynamicFetcher/StealthyFetcher and their session classes already support executable_path.
• Tests run:
  • ./.venv313/bin/python -m pytest tests/ai/test_ai_mcp.py::TestExecutablePath tests/cli/test_cli.py -q
  • ./.venv313/bin/python -m ruff check scrapling/
  • ./.venv313/bin/python -m ruff format --check scrapling/ --diff
  • ./.venv313/bin/python -m mypy scrapling/
  • ./.venv313/bin/python -m pyright --pythonpath ./.venv313/bin/python scrapling/
  • git diff --check

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doc-strings.

[yetval]

Hey @samrusani, Nice work on this. I read it through against #347, and it does what was asked, with a clean setup! The executable path flows through the browser tools the right way, the global default, and per-call override both work. Two tiny things: if you ever want to polish, an empty path string is treated as unset, and a per-call path is ignored when a session id is reused, though neither blocks merging. Thanks for putting this together, this is quite helpful!!

[D4Vinci]

Thanks @samrusani for solving this one, and thanks @yetval for your review.