Add trace diagnostics settings panel

[rogierx]

Addresses #18.

This adds a compact trace diagnostics settings panel to the webview so users can tune trace time/type/total-type thresholds without leaving the trace UI. Threshold updates are sent through typed webview messages, validated against known extension configuration keys, and persisted to the workspace configuration so each project can keep its own settings.

The panel also exposes the relative/absolute diagnostics mode next to the threshold controls.

The branch removes package-manager caching from the tag-triggered release workflow so the publish/release path does not rely on shared caches.

Validation:

• pnpm exec vitest run test/index.test.ts
• pnpm run typecheck
• pnpm exec eslint shared/src/messages.ts src/configuration.ts src/handleMessages.ts ui/src/appState.ts ui/components/TraceSettings.vue ui/app.vue test/index.test.ts
• pnpm exec nuxt build ui
• pnpm exec rollup -c
• git diff --check