fix(client-handover): PDF render bugs — marked CLI, white cover, PNG logo

Three bugs surfaced on the LIVRAISON.pdf test render:

1. **MD→HTML conversion** — host had no pandoc, no python-markdown, fell
   back to `npx marked < "$src"`. marked CLI 16.x ignores stdin and
   dumps its own cli.js source. Resulting PDF body = marked's binary
   source (`#!/usr/bin/env node`, `Marked CLI`, copyright). Fix:
   `npx --yes marked --gfm -i "$src"` (file path via -i, not stdin).

2. **Cover background** — original cream `#F5F0EB` + 8mm green stripe
   was washed out. Iterated to white-pure bg with subtle radial
   sage/forest tints, black-deep title, green-forest accents
   (eyebrow, meta labels, footer, border). Solid green-dark tried
   first then rejected (too heavy for long client-facing doc).

3. **Default logo** — SVG `logo-horizontal.svg` rendered cream-toned,
   blended into bg. Switched LOGO_URL default to
   `https://zenquality.fr/assets/logo-horizontal-1024.png`.

Also added test-artifact gitignore rules for LIVRAISON.* / HANDOVER.*
project-local renders.

Verified: regenerated LIVRAISON.pdf → 164 KB, 19 pages, full content
rendered, white cover with black title + green-forest accents +
visible PNG logo.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -86,6 +86,14 @@ hooks/node_modules/
 graphify-out/
 .ctx7-cache/
 
+# /client-handover test artifacts (project-local renders)
+LIVRAISON.md
+LIVRAISON.html
+LIVRAISON.pdf
+HANDOVER.md
+HANDOVER.html
+HANDOVER.pdf
+
 # Install logs
 install-*.log