feat(pipeline): InDesign output generator — FSE patterns, templates & theme.json writer (#65)

[PAMulligan]

Sub-issue of #61. Implements stage 4 of the InDesign-to-WordPress pipeline: take the parsed IR (#62/#63) and mapped design tokens (#64) and emit the actual WordPress artifacts — a complete, installable Flavian-compatible FSE theme.

What it does

generateTheme(ir, options) → a full theme directory (pure & deterministic, no fs/clock/randomness in the core):

• Patterns — one block pattern per spread, filed under an InDesign Imports category. Frames map to core blocks:
  • text frames → core/heading / core/paragraph, grouped in core/group (role from the paragraph style name: Heading N, Body, Caption…)
  • image frames → core/image, or core/cover when text is overlaid on the image
  • side-by-side frames → core/columns
  • all typography/color references use token slugs from [InDesign pipeline] Style and design-token mapper (paragraph/character styles + swatches → theme.json) #64, never inline values
• Template parts — header.html / footer.html derived from master-spread chrome (web-appropriate defaults when no usable master)
• Templates — index.html (stitches the spread patterns between header/footer), page.html, 404.html
• theme.json — the token mapper's merged base + partial (already schema-valid)
• Media — deterministic staged-asset plan + bin/import-media.sh; optional bin/seed-content.sh (--seed-content)
• Report — indesign-pipeline-report.md enumerating produced files, unmapped IR nodes, and manual follow-ups

Exposed via a new flavian-generate-theme CLI that composes with the parser CLIs or parses .idml/.pdf directly. Image URLs resolve through get_theme_file_uri() (pattern-first — no broken src="").

Acceptance criteria

• End-to-end on a fixture .idml produces a theme dir that loads in the Site Editor without PHP errors
• ≥1 pattern per spread appears under the "InDesign Imports" category (registered in functions.php)
• theme.json round-trips through validation (it's the mapper's already-validated merged output; a test also asserts every slug referenced in patterns exists in theme.json)
• Generation report enumerates produced files and unmapped IR nodes
• Snapshot tests cover generated markup for a text-heavy and an image-heavy spread (tests/indesign/__snapshots__/)
• Patterns are deterministic given the same IR (byte-identical reruns — covered by a test)

Tests

pnpm --filter @flavian/pipeline test → 99 passing (88 prior + 11 new). Snapshots re-record with UPDATE_SNAPSHOTS=1.

Notes

• Layout lives in packages/pipeline/src/indesign/generate/; docs in docs/pipeline/indesign-output-generator.md.
• Also registered the existing-but-unregistered flavian-map-tokens bin alongside the new one.
• ajv/ajv-formats (pipeline devDeps) were materialized via pnpm install (lockfile unchanged) so the mapper's schema-validation tests run.

🤖 Generated with Claude Code