feat: sweep complet — tous les émojis → outline SVG icons

Templates modifiés (22 fichiers):
- _icons.html: +14 new icons (paperclip, external-link, sparkles, lightbulb, tag,
  file-text, save, upload, trending-up, zap, alert-triangle, user, eye-off)
- base.html: +8 JS icons, 🦎🐙🔑🔗👁📋🔲📑❓⚠️→SVG
- page_editor.html: 43→0 émojis (📎📄🔒🔗⭐📋📁✨📝🗄📑📊📅🗓🖼📥🌐✏💬💡 etc)
- settings.html: 30→0 (⚙️📋🏷🧩👥💾🙈👁🔒🌙☀️🌳📊📝⚠🦎✅🐙🔗✏🗑)
- local_workspace.html: 25→0 (📄📁✏🗑⚠📋➕)
- gitea_workspace.html: 25→0 (🔗📄📤🔄⚙📁📄🔒✏🗑💾)
- board.html: 13→0 (📁📊📋☰📈👥✕✓🗑⚡🔍)
- workspace.html: 11→0 (🏠🔑⚙📁🔗📂🐙)
- landing.html: 8→0 (📚🚀📝📊🦎🌐🔒⚡)
- trash.html, table_view, dashboard, accounts, card_detail, public_page,
  workspaces, team_load, notes, _header, detailed_board, card, board_fragment
- Ajouté import _icons.html aux fragments standalone
- 143 tests passent

app/templates/notes.html

@@ -15,7 +15,7 @@
     <form hx-post="/notes/{{ owner }}/{{ repo }}" hx-target=".notes-editor" hx-swap="outerHTML">
       <textarea name="content" class="notes-textarea" placeholder="Notes markdown pour ce projet...">{{ content }}</textarea>
       <div class="notes-actions">
-        <button type="submit" class="btn btn-primary">💾 Sauvegarder</button>
+        <button type="submit" class="btn btn-primary">{{ fd_icon("save",14) }} Sauvegarder</button>
       </div>
     </form>