Summary

This PR finishes the DocFX site rollout for ModularityKit.Mutator by turning the generated docs into a styled, navigable documentation site with package scoped API entry points, custom theme, and responsive layout.

Highlights

DocFX site structure

• Ada real root homepage at index.md and wire it into the DocFX build.
• Replace hand maintained Docs/API/API.md and Docs/API/Redis.md pages with generated API entry points.
• Keep API output grouped by package under obj/api/core, obj/api/governance, and obj/api/redis.
• Add NamespaceDoc coverage for governance package roots so generated reference starts at the expected namespace surface.

Custom theme and navigation

• Add custom DocFX theme under templates/modularitykit.
• Style the site with branded navigation, homepage sections, dark API surfaces, and package-aware active tabs.
• Remove the homepage right-side contribution panel and let the center content use the full width.

API usability and responsive behavior

• Add API sidebar behavior for expand/collapse and side panel toggling through templates/modularitykit/styles/main.js.
• Split responsive rules into a dedicated templates/modularitykit/styles/mobile.css stylesheet.
• Rework the mobile navbar into a usable stacked layout with a separate collapsed panel.
• Normalize API page spacing and homepage layout so generated pages read consistently across desktop and mobile.

Why

Issue #52 started as API reference publishing from XML documentation, but the practical gap was larger than generation alone. Without a real homepage, package-scoped entry points, navigation that matched repository structure, and a usable mobile layout, the published output was technically generated but still not fit to serve as the repository docs site.

This PR makes the generated DocFX output usable as the primary documentation surface while keeping the source of truth in XML docs and Markdown already present in the repository.

Checks

• docfx docfx.json

Closes

• Closes [Task]: Add API reference publishing from XML docs #52