Master's left sidebar grew global main panels, so the manager leaves the
Settings dialog: `ui-settings-plugin-manager` registers a `sidebar.panellist`
entry and the `main` panel it opens under one id, `plugins`, and the former
tab becomes `PluginManagerPage` with its own heading, intro, refresh, and
Add plugin, scrolling inside the main column. Plugin configuration stays in
the Settings Plugins section, which `ui-settings-plugins` now renders
without a tab strip when it holds one contribution.
Web e2e reaches the manager through the sidebar; the plugin-config,
plugin-manager, settings-chrome, and lifecycle-chrome scenarios and goldens
follow. The decision and why configuration does not move are in the new
Agent Note, cross-linked from the two notes it revises.
Yichen Jiang
0aeebb017e