Refresh hero demo GIF to cover 1.8.x features (Capability Map, EventStorming, Markdown export)

[KKranthi6881]

Context

The hero demo GIF in README.md (currently demo/demo.gif, embedded at line ~132) was recorded during the 1.4.x era. It demonstrates dbt readiness scores, model diagrams, validation findings, and AI-assisted YAML fixes — all still accurate, but it predates everything that landed in the 1.8.x release thread.

The README now has a "What's new in 1.8" matrix flagging four features that aren't visible in the GIF, so first-time viewers see the matrix and the GIF telling different stories.

What to capture in a refresh

1. Capability Map top-tab — boxes-in-boxes hierarchy of Domain → Subject area → Concept, with the search box filtering live (Phase 3 / 1.8.0)
2. EventStorming canvas — open commerce_eventstorming.diagram.yaml from the jaffle-shop tutorial repo; the canonical sticky-note palette (orange/blue/yellow/pink/amber) should be visible (Phase 4a / 1.8.1)
3. EventStorming flow narrative in DocsView — switch the same file to the Docs tab; the numbered narrative grouped Actors → Commands → Aggregates → Events → Policies should render between the ER diagram and the per-entity tables (Phase 4b / 1.8.2)
4. Export Markdown button click → file downloads → paste into a fresh GitHub issue and watch the mermaid block render inline (Phase 5a / 1.8.2)

Suggested recording approach

• Use the jaffle-shop-DataLex repo as the working project (already version-pinned to 1.8.2 and contains the new commerce_eventstorming diagram)
• 30–45 seconds total, looped
• Keep the dbt readiness / AI YAML-fix moments — they're still relevant — and append the four new beats above

Why this is a separate issue

Recording / editing a GIF is creative work that doesn't belong in a code PR. Flagging this so it gets picked up after the 1.8.2 release lands.

Acceptance

• New demo/demo.gif (or demo/demo-1.8.gif with README updated to point to it) shows all four 1.8.x features
• README alt-text updated to reflect the new content
• File size still reasonable for inline rendering on github.com (<10 MB)