feat: show Ollama plugin badge and available LLM models on marketplace cards

Backend:
- Add attributes field to MarketplaceOfferView schema
- Include attributes in _to_offer_view() response

Frontend:
- Add attributes type with Ollama fields to OfferRecord
- Show purple 'Ollama' plugin badge on cards with models
- Display available LLM model tags (gemma3, deepseek-r1, etc.)
- Add plugin-badge and model-tag CSS styles

apps/marketplace-web/src/main.ts

@@ -151,6 +151,14 @@ function renderOffers(offers: MarketplaceOffer[]): void {
               <span class="spec-value">${formatNumber(offer.capacity)} units</span>
             </div>
           </div>
+          ${offer.attributes?.models?.length ? `
+          <div class="offer-plugins">
+            <span class="plugin-badge">Ollama</span>
+          </div>
+          <div class="offer-models">
+            <span class="models-label">Available Models</span>
+            <div class="model-tags">${offer.attributes.models.map(m => `<span class="model-tag">${m}</span>`).join('')}</div>
+          </div>` : ''}
           <div class="offer-pricing">
             <div class="offer-price">${formatNumber(offer.price_per_hour ?? offer.price, { minimumFractionDigits: 2, maximumFractionDigits: 2 })} <small>credits/hr</small></div>
             <div class="offer-sla">${offer.sla}</div>