Redesign dashboard and transparent companion

[noisy]

The dashboard and companion used tactical styling with dense typography and inconsistent controls. This redesign introduces graphite surfaces, readable conversation bubbles, consistent header actions, larger voice identities, and a horizontal turn-history timeline.

The companion keeps transparent gaps over light and dark backgrounds, combines its drag handle with the session header, and preserves scrollable history at 280 × 200 pixels. Synthetic companion previews are narrower and expose a width control.

Storybook now includes isolated dashboard and companion scenarios. Speech-test mocks are scoped to their stories, and production Storybook builds no longer reload the development preview. The changes are organized into nine focused commits.

Validation

• 202 frontend tests passed across 23 files.
• All 114 Storybook stories passed a browser render smoke check.
• Dashboard typecheck/build, Storybook production build, and website build passed.
• Rendered checks covered desktop/mobile layouts, light/dark transparency, keyboard scrolling, state changes, and height-only resizing.
• Native Electron dragging, always-on-top behavior, and a real PiP window were not exercised.

Detailed results and limits: docs/superpowers/specs/2026-09-05-interface-redesign-verification.md.