Fix Chrome/browser errors during ingestion on other machines

[CaioHAndradeLima]

Problem

• linkedin-jobs-collect.sh always used hardcoded UVX=/Users/caio/.local/bin/uvx and never .venv → fails on other Macs/clones.
• linkedin-deep-collect.sh had the same hardcoded uvx fallback.
• With JOBSEARCH_COLLECT_HEADED=1, preflight reported browser ready whenever channel=chrome was set, even if Google Chrome was not installed → ingestion then failed at launch (“no Chrome”).

Fix

• Shared scripts/lib/run_collect_python.sh: prefer .venv/bin/python3, then uvx on PATH (or UVX env if set).
• Headed collect readiness: require installed Chrome or Patchright Chromium (make browser), not channel alone.
• Clearer error text for headed vs headless; extra Linux/Windows Chrome paths.

For users hitting the error today

make install && make browser
make doctor
# If they don't need visible Chrome:
unset JOBSEARCH_COLLECT_HEADED   # or restart UI without that env
make ui

Test plan

• pytest tests/retrieval/test_session_extended.py::test_headed_collect_ready_without_chrome_requires_bundled
• Michele: make pull, make browser, ingestion from UI

Made with Cursor