Add Mainland China proxy routing with independent rule workspaces.
Preserve existing routing choices through equivalent preset mappings.
BREAKING CHANGE: existing custom rules and enablement settings are
not migrated. Recreate them in the appropriate preset.
Replace the inline RulesDeletionButton with a toolbar delete button
(trash icon next to the add button). It is enabled only when the
custom-rules source is selected on the left and the selection contains
deletable custom rules; the collection must also be complete and not
committing.
The table context menu gains a destructive "删除 (N)" item after a
divider when the custom-rules source is selected, with the same
enablement conditions. Both entries share one confirmation alert now
held by RulesView.
Also inline the operation status view into the filter row and tighten
filter-area padding.
Qiu Yuzhou