fix(tools): apply Browser Use headless profile

[MagMueller]

What

• pass BrowserProfile(headless=...) to the current Browser Use Agent
• keep the legacy browser-use-py310x kwargs path for Python 3.10
• reject unsupported Firefox and WebKit choices instead of silently ignoring them
• add regression tests for the current Browser Use configuration path

Why

BrowserUseBase stores browser_type and headless, then passes them as extra Agent kwargs. Current Browser Use accepts those kwargs but does not apply them, so EvoAgentX's default headless=True can still launch a visible browser.

Validation

• focused tests on Python 3.11 with Browser Use 0.13.8: 2 passed
• Browser Use 0.13.8 applies BrowserProfile(headless=True)
• ruff check tests/test_browser_use.py
• ruff format --check tests/test_browser_use.py
• repository-wide Ruff baseline unchanged: 6,240 diagnostics on main and this branch
• git diff --check
• TruffleHog: 0 verified and 0 unverified secrets