test(ui): make Product Storybook baselines production-faithful and CI-rendered #1489

Problem

Product Storybook stories are used as the visual baseline for UI review, but the baseline is not currently fail-closed:

• some stories mount inner panels in hand-built frames instead of the production page host;
• the global Storybook decorator adds geometry to every story, including layout: 'fullscreen' Product stories;
• narrow stories can shrink an inner wrapper without changing the viewport, so viewport media queries are not exercised;
• CI typechecks story source but does not render all Product stories or run their play functions;
• there is no manifest showing which product surfaces, states, hosts, and viewports the smoke gate covers.

This leaves a gap between “the story exists” and “the story is a faithful, renderable visual baseline.” It also allows render failures and console.error output to pass CI.

Refs #390, #1433, #1452, and #1303. This issue is governance only; it does not redesign those pages.

Production-faithful hosts

• Make the shared Storybook decorator geometry-neutral for Product/* stories.
• Keep padding or scaffolding explicit for Primitives/* and Design System/*.
• Mount module stories through their production page entry points instead of mounting inner panels in copied frames.
• Keep Settings and shell stories on the closest production-owned host available; do not copy production class chains into story-only wrappers.

Viewport matrix

Define three named Product-story viewports and use the real iframe viewport:

• wide: 1280px
• compact: 820px
• floor: 480px

A surface may opt out only with a reason in the coverage manifest.

Coverage manifest

Add one checked-in manifest for the required Product visual-smoke surface. Each entry identifies:

• story id;
• production host;
• required viewport or viewports;
• user-reachable state represented by the story.

The check must fail when a required entry is missing, references an unknown story, or no longer renders.

CI render/play smoke

After building Storybook, CI visits every manifest entry and:

• waits for the story and its play function to settle;
• asserts that the story root rendered non-empty content;
• fails on uncaught page errors, unhandled promise rejections, or console.error;
• runs at every required viewport.

Use the existing Storybook renderer substrate. This is a render and interaction smoke gate, not a pixel snapshot suite.

Acceptance

• Product/* stories receive no implicit page padding or other global layout geometry.
• Skills, MCP, Plan reminders, and Daily Review baseline stories use production page hosts.
• The checked-in manifest includes Settings and all four module subpages, with wide, compact, and floor coverage or an explicit opt-out.
• CI builds Storybook and renders every manifest entry.
• Story play functions run in CI and failures fail the job.
• Uncaught errors, unhandled rejections, and console.error fail with the story id and viewport in the report.
• Negative contracts prove that an unknown story id, missing manifest entry, render exception, and emitted console.error each fail the gate.
• Existing typecheck, Electron E2E, and computed-style contracts remain green.

Non-goals

• No page redesign or component-vocabulary changes.
• No screenshot baseline or pixel-diff service.
• No generic module-page framework.
• No replacement of built-app verification for geometry claims.
• No provider-specific E2E expansion.