Converge plan site renderer with shared layout engine

Approach

Phase 1 — Extend planLayout config

Add computed.toc and restructure the main slot in packages/transform/src/layouts.ts to include a ToC aside and content wrapper, following the docsLayout pattern:

computed: {
    toc: {
        type: 'toc',
        source: 'headings',
        options: { minLevel: 2, maxLevel: 3 },
        visibility: { minCount: 2 },
    },
},

Add a content wrapper with conditionalModifier for has-toc and a ToC aside sourced from computed:toc.

Phase 2 — Wire renderPage to the layout engine

Replace the manual HTML assembly in renderPage() with a call through the shared layout engine. The nav region builder output feeds into the region:nav slot. Page content feeds into the content source. The layout engine handles structure, conditional slots, and computed content.

The local planTheme manifest and planLayout in render-pipeline.ts can be removed once the shared config is authoritative.

Phase 3 — Migrate inline behaviors

Move the inline <script> blocks (sidebar collapse/search, copy-to-clipboard) to proper behavior entry points that the layout engine can inject. Options:

• Add them to planLayout.behaviors array if they can be standard @refrakt-md/behaviors modules
• Or keep them as plan-specific scripts injected via the engine's script slot

Phase 4 — Add ToC CSS

Add plan-specific ToC styles (.rf-plan-toc) to runes/plan/styles/default.css, following the sticky aside pattern from packages/lumina/styles/layouts/docs.css. The ToC should sit to the right of .rf-plan-main content.