Compact tool UI: move setting to UI section + add negative tests

[edelauna]

Follow-up from PR #327 review.

1. Move compactToolUI toggle to UISettings

compactToolUI is a display preference (how chat rows render), but it's currently in the Context Management settings section alongside settings that control model context (maxOpenTabsContext, maxWorkspaceFiles).

It belongs in UISettings.tsx, next to reasoningBlockCollapsed (collapse thinking blocks) and enterBehavior.

Files to update:

• webview-ui/src/components/settings/ContextManagementSettings.tsx — remove compactToolUI prop + checkbox
• webview-ui/src/components/settings/UISettings.tsx — add compactToolUI prop + checkbox
• webview-ui/src/components/settings/SettingsView.tsx — pass compactToolUI to UISettings instead of ContextManagementSettings

2. Add negative-path regression tests

ChatRow.compact-tool.spec.tsx only tests the happy path (compactToolUI=true, isExpanded=false). Two negative cases are missing:

• isExpanded=true → compact row must NOT render
• compactToolUI=false → compact row must NOT render

These guard against accidentally removing either condition from if (compactToolUI && !isExpanded).

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Ref: #327