Add browser profile picker to web app setup

[cbullard]

Summary

• discover profiles for the effective Chromium-family web app browser
• offer an optional profile picker when the interactive wizard finds multiple profiles
• store the selected --profile-directory directly in the generated desktop launcher
• keep Automatic as the default, preserving current behavior
• hide the picker when profile selection would be redundant

The direct launcher binding keeps the choice visible and portable, requires no separate runtime profile store, and lets other desktop-entry work inspect the selected profile.

Browser support

Profile discovery follows the browsers already supported by omarchy-launch-webapp: Chromium, Chrome, Brave, Brave Origin, Edge, Opera, Vivaldi, and Helium. Unsupported default browsers continue to use Chromium's profile state because web apps already fall back to Chromium.

Related work

#6105 proposes a broader profile-aware runtime for the older dev branch, including remembered launch-time choices. This is an independent, narrower Quattro implementation: it binds a profile only during web app creation and writes the choice into the launcher itself.

Testing

• bash test/shell.d/webapp-browser-profile-test.sh
• bash test/shell.d/webapp-install-test.sh
• bash test/shell.d/webapp-name-test.sh
• bash test/shell.d/webapp-install-escaping-test.sh
• ./test/cli
• ./test/shell — 221 of 226 files passed; the same five unrelated graphical/package-coverage failures reproduce on untouched origin/quattro
• exercised against an isolated copy of a real six-profile Chromium Local State; generated launcher passed desktop-file-validate and preserved Profile 2 as one argument