[codex] Add Binary Ninja Python execution tool

[farvend]

What changed

• Add execute_python backed by Binary Ninja's persistent Python scripting provider.
• Expose one POST endpoint: /executePython.
• Capture output, warnings, and errors with a 1,000,000-character limit.
• Enforce 0.1–300 second timeouts and discard timed-out contexts.
• Avoid logging submitted source code.
• Mark the MCP tool destructive, non-idempotent, and open-world.

Why

Some analysis and automation operations require direct Binary Ninja API access that cannot be expressed through the existing fixed endpoints.

Impact

MCP clients can run multi-line Python with console variables such as bv. This is intentionally a high-risk capability and should be confirmed by clients.

Dependency

This branch is stacked on the tool-annotations branch. Its diff against main will shrink after that PR merges.

Validation

• python -B -m unittest discover -s tests -p "test_*.py" (6 tests)
• npm run build
• npm run test:annotations (55 tools)