Simplify the web example UI and UX

[jerelvelarde]

The web example opened an incident list, detail panels, a long prompt guide, and chat at once. Simplify it to a compact incident view beside an inline assistant, with a dropdown for switching incidents and expandable details and timeline.

Replace the prompt guide with two chat starters, shorten the follow-up form and copy, and simplify the responsive styling. Page context, frontend tools, agent-rendered cards, and session-only follow-ups retain their existing behavior. Update the page metadata and template guide to match.

Validation:

• Prettier and diff hygiene checks.
• All workspace typechecks and root tests; MCP stdio protocol check.
• Production web build (passes with the dependency-expression warning in the Google Vertex SDK dependency).
• Browser checks for selection, follow-up creation and validation, refresh behavior, chat starters, and desktop/mobile layouts at 320px and 390px.

Live assistant responses were not tested because this checkout has no model credentials configured.