feat(browser): auto-detect chromium browsers for bridge

[umnooob]

Related issue: #742

Summary

This PR improves Browser Bridge connection behavior in two steps:

1. Auto-detect supported Chromium-based browsers
2. Prefer already-running browsers before launching new ones

Supported browser family order remains fixed:

• Chrome
• Edge
• Chromium

Connection attempts now work like this:

• detect installed browsers
• split them into running and non-running candidates
• try running candidates first, preserving the same brand order
• then try non-running candidates, preserving the same brand order

It also lets opencli doctor show the browser inferred from this run when connectivity is established during
the current attempt.

Included commits

• 9f9705c feat(browser): auto-detect chromium browsers for bridge
• f2af57b feat(browser): prefer running browsers for bridge

What changed

Browser auto-detect

• detect installed stable Chromium-based browsers on macOS / Linux / Windows
• support:
  • Chrome
  • Edge
  • Chromium

Running-browser preference

• detect which supported browsers are already running
• reorder connection attempts so running browsers are tried first
• preserve the existing brand order inside each group

Doctor inference

• when the extension connects during the current run, doctor reports the inferred browser for that run
• no extension protocol changes
• if the extension was already connected before the run started, doctor does not pretend to know the browser

Messaging

• keep Chromium-based wording in install/help text
• keep detected/tried browser info in failure output

Files changed

• src/browser/candidates.ts
• src/browser/candidates.test.ts
• src/browser/bridge.ts
• src/browser.test.ts
• src/doctor.ts
• src/doctor.test.ts
• src/execution.ts
• src/doctor.ts
• scripts/postinstall.js

Notes

• no new config
• no CDP fallback
• no extension handshake/browser identity protocol changes
• doctor browser display is inference from the current run only

Type of Change

• ✨ New feature

Checklist

• I ran the checks relevant to this PR
• I updated tests or docs if needed
• I included output or screenshots when useful

Screenshots / Output