fix: /local-workspace SVG rendering + ALL emoji icons converted

- BUG: x-text→x-html pour _fileIcon() (SVG s'affichait en texte brut)
- _fileIcon(): 11 types de fichiers → SVG (🐍📕🖼️📜🌐🎨🗃️💻⚡📦📄)
- title-card: x-text '📁' → x-html getSvgIcon('folder',24)
- preview empty states (PDF): 📕 → getSvgIcon('file')
- toolbar: 🔍📄📁🗑 → SVG icons
- filter chips: 📁📝📕🖼️📜 → getSvgIcon()
- view menu: 🌳📋📊🏷️📝 → text-only (clean)
- _icons.html: +image, +download
- getSvgIcon JS: +image, +download, +search, +home
- 143 tests passent

app/templates/_icons.html

@@ -48,6 +48,10 @@
 <svg width="{{s}}" height="{{s}}" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><line x1="12" y1="5" x2="12" y2="19"/><line x1="5" y1="12" x2="19" y2="12"/></svg>
 {%- elif name == 'bell' -%}
 <svg width="{{s}}" height="{{s}}" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M18 8A6 6 0 0 0 6 8c0 7-3 9-3 9h18s-3-2-3-9"/><path d="M13.73 21a2 2 0 0 1-3.46 0"/></svg>
+{%- elif name == 'image' -%}
+<svg width="{{s}}" height="{{s}}" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><rect x="3" y="3" width="18" height="18" rx="2" ry="2"/><circle cx="8.5" cy="8.5" r="1.5"/><polyline points="21 15 16 10 5 21"/></svg>
+{%- elif name == 'download' -%}
+<svg width="{{s}}" height="{{s}}" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M21 15v4a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2v-4"/><polyline points="7 10 12 15 17 10"/><line x1="12" y1="15" x2="12" y2="3"/></svg>
 {%- elif name == 'chevron-down' -%}
 <svg width="{{s}}" height="{{s}}" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><polyline points="6 9 12 15 18 9"/></svg>
 {%- elif name == 'inbox' -%}