feat(make-pdf): --to html|docx output formats

--to html writes the assembled self-contained document directly (no print
round-trip): inline vector diagrams, data-URI images, zero network
references, plus an @media screen layer for browser reading. --to docx is
the content-fidelity export (eng-review P8): html-to-docx@1.8.0 (exact pin;
pure JS, bun-compile-verified) maps headings/tables/code/lists; diagrams and
SVG images rasterize at 300dpi of the content-box width via the render tab;
diagnostic figures convert to plain p/pre so the converter can't silently
drop an error. --format keeps its page-size-alias meaning; --to is the
output format, and the CLI says so when confused.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

make-pdf/src/print-css.ts

@@ -137,6 +137,23 @@ function pageRules(size: string, margin: string, opts: PrintCssOptions): string
   ].filter(line => line !== "").join("\n");
 }
 
+/**
+ * Screen layer appended for `--to html` exports. The print CSS stays the
+ * source of truth; this only makes the same document readable in a browser
+ * (centered measure, padding, no print-only chapter breaks forcing scroll
+ * gaps). Print output is unaffected — media-scoped.
+ */
+export function screenCss(): string {
+  return [
+    `@media screen {`,
+    `  body { max-width: 52em; margin: 0 auto; padding: 2.5em 1.5em; }`,
+    `  .chapter { break-before: auto; }`,
+    `  .watermark { display: none; }`,
+    `  figure.diagram { overflow-x: auto; }`,
+    `}`,
+  ].join("\n");
+}
+
 function rootTypography(): string {
   return [
     `html { lang: en; }`,