Show which processes hold the Breeze UI ports when start-airflow fails

[Andrushika]

Why

Follow-up of #71241: breeze start-airflow --dev-mode fails early when port 5173 or 5174 is taken. But the message only says the port is in use. Users then need to run lsof themselves to see which processes hold the ports before they can stop them, which is a bit annoying. Most of the time it is just a stale Vite dev server left over from a previous breeze run.

What

Look up the listening process with psutil and print its PID and command line, plus a kill <pid> hint. If the listener cannot be found (for example no permission), the old message is kept. psutil is bumped to >=6.0.0 because Process.net_connections() was added there.

Before:

Cannot start UI development servers because the following local port(s) are already in use: 5173, 5174.
Stop the processes using these ports and try again.

Now:

Cannot start UI development servers because the following local port(s) are already in use: 5173, 5174.
Port 5173 is used by PID 5771: node /Users/andrewchang/Dev/github.com/airflow/airflow-core/src/airflow/ui/node_modules/.bin/../vite/bin/vite.js —port 5173 —strictPort
Port 5174 is used by PID 5793: node /Users/andrewchang/Dev/github.com/airflow/airflow-core/src/airflow/api_fastapi/auth/managers/simple/ui/node_modules/.bin/../vite/bin/vite.js —port 5174 —strictPort
Stop the processes using these ports (for example kill 5771 5793) and try again.

related: #71241

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Was generative AI tooling used to co-author this PR?

• Yes — Claude Code (Fable 5.1)

Generated-by: Claude Code (Fable 5.1) following the guidelines

[SameerMesiah97]

Could we also add testcoverage for the best-effort failure handling in _find_local_port_listeners, particularly when inspecting a process raises psutil.Error?

[Andrushika]

Added a test: test_find_local_port_listeners_skips_processes_that_cannot_be_inspected, thanks for reviewing!