fix(python): close browser server on launcher shutdown

[Cloudymap1e]

Related Issue

Closes #172

Description

The Python server launcher previously closed stdin immediately after sending configuration, while the Node process then used that same stream only as a keepalive. That prevented stdin EOF from representing controller shutdown and left BrowserServer cleanup dependent on abrupt process termination.

Python now sends one newline-delimited base64 configuration frame and keeps the pipe open. The Node launcher parses exactly that first frame, latches early stream termination, and treats later stdin end, close, or error as a shutdown request. It closes BrowserServer before exiting so Playwright can remove its temporary profile. The Python side closes the control pipe and reaps the child with bounded terminate/kill fallbacks for interruptions during write, flush, or wait.

Type of Change

• Bug fix
• New feature
• Documentation update
• Other

Testing

• python -m pytest pythonlib/tests/test_server.py -q: 8 passed
• python -m pytest pythonlib/tests -q: 48 passed, 4 skipped
• node --check pythonlib/camoufox/launchServer.js: passed
• The focused tests use real Node subprocesses to cover split/combined framing, first-frame-only parsing, clean EOF, close-only termination, stream errors, BrowserServer close completion, and interrupted Python write/flush cleanup

Fingerprint Report

Not applicable: this changes the Python/Node server lifecycle and does not alter fingerprint behavior.

Checklist

• I have linked a related issue above
• My changes are focused on a single logical change
• I have added testing instructions which include the desired result
• Service tests pass (for python library changes) -./service-tester/run_tests.sh --browser-version official/prerelease/146.0.1-alpha.25 (attach screenshot) temporarily out of service lol
• Build test passes (for patch changes) - not applicable to this server-lifecycle change