Add widgetConfig docs and interactive demo

[matipojo]

Summary

• Add a dedicated widgetConfig guide covering all fields, layout defaults, v1/v2 usage, and production patterns from Elementor hosts (my.elementor help center + visitor floating widget).
• Add an interactive demo at demo/load-sidebar-v2-widget-config/ with three presets (helpCenter, visitor, sandbox), live resolved JSON, and window.angieConfig override support.
• Link the new docs and demo from the root README, loadSidebarV2 README, and demos index.

Test plan

• Run npm run demo and open /demo/load-sidebar-v2-widget-config/?preset=helpCenter
• Verify two-column layout (JSON + Common fields) does not overlap
• Open Angie sidebar — confirm it docks on the right without covering page content
• Switch presets via ?preset=visitor and ?preset=sandbox and confirm layout/config changes
• Override copy via window.angieConfig in the console and reload

✨ PR Description

1. Problem & Context

Angie SDK lacks user-facing documentation and interactive examples for widgetConfig — the key API for customizing embedded chat UI (copy, features, MCP focus). This PR ships comprehensive docs plus a production-patterned demo with runtime overrides.

2. What Changed (Where)

File	Purpose
src/load-sidebar-v2/widget-config.md	Full reference: field types, layout defaults, production patterns (help center, visitor widget), window.angieConfig runtime override pattern
demo/load-sidebar-v2-widget-config/	Three interactive presets (help center sidebar, visitor floating search, feature sandbox) with live config JSON inspector and console override hints
src/load-sidebar-v2/README.md, README.md	Links to new docs and demo; export list now includes WidgetConfig type
demo/index.html	New featured card linking to widget-config demo

3. How It Works

Demo host (host.js) reads ?preset= param → builds widgetConfig via preset-specific builders → calls sdk.loadSidebarV2({ widgetConfig }) → JS renders resolved config as JSON and highlights active preset. Users can override window.angieConfig in console before reload to test copy/prompts without rebuilding. localServers.skipLoading: true pattern shown to avoid MCP registration race. CSS (demo-host.css) mirrors Elementor production UI tokens and right-docked sidebar layout.

4. Risks

None material. Demo is isolated; docs are additive reference. Only note: window.angieConfig override pattern in demo assumes hosts will inject that global — document clearly that this is optional and for iteration only, not production auth/secrets (already done in widget-config.md § Runtime overrides).

Generated by LinearB AI and added by gitStream.
_{AI-generated content may contain inaccuracies. Please verify before using.
💡 Tip: You can customize your AI Description using Guidelines Learn how}