republik-style redesign: dark masthead, hero block, palette, pills

- Dark full-bleed masthead with serif wordmark and stacked nav
- Hero entry treatment: full-bleed image bg with gradient overlay
- Per-section color system (data-section) + per-post override (data-color)
- Japanese accent palette (ajisai, sakura, suna, ichigo, yuyake, sora,
  kusa, kori, amagumo, yuki) — set via `color:` in front matter
- Tag pills replace hashtag-style tags; rendered as sibling of card link
  to avoid invalid nested <a> elements
- Single article: clean Republik-style header, no section rubric,
  tags as pills at bottom
- Cover image support (`cover_image:` in front matter):
    - wide mode: full-card banner above text
    - icon mode: small thumbnail right of text with colored card bg
- Library subsection header redesigned with section-colored stripe
- Dates use Swiss DD.MM.YYYY display (ISO retained in datetime attr)
- Custom Tokyo metro photo as demo cover image

content/library/software/dossier.md

@@ -5,6 +5,9 @@ weight: 10
 tags: ["software", "eigene-werkzeuge"]
 summary: "Projektorganisation für ein Architekturbüro — von der Anfrage zur Übergabe."
 external: "https://dossier.gabrielevarano.ch"
+color: kori
+cover_image: /images/tokyo-metro.jpg
+image_mode: icon
 ---
 
 **DOSSIER** ist die Projektverwaltung von OPENBUREAU.