fix(chat-web): select default model instead of first model

- Update chat store to find model with isDefault: true
- Fix model selection in chat page and spaces page
- Falls back to first model if no default is set

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

apps/chat/apps/web/src/lib/stores/chat.svelte.ts

@@ -47,7 +47,9 @@ export const chatStore = {
 		try {
 			models = await chatService.getModels();
 			if (models.length > 0 && !selectedModelId) {
-				selectedModelId = models[0].id;
+				// Find default model, or fall back to first model
+				const defaultModel = models.find((m) => m.isDefault);
+				selectedModelId = defaultModel?.id || models[0].id;
 			}
 		} catch (e) {
 			error = e instanceof Error ? e.message : 'Failed to load models';

apps/chat/apps/web/src/routes/(protected)/chat/+page.svelte

@@ -37,7 +37,9 @@
 		dataLoaded = true;
 		models = await chatService.getModels();
 		if (models.length > 0) {
-			selectedModelId = models[0].id;
+			// Find default model, or fall back to first model
+			const defaultModel = models.find((m) => m.isDefault);
+			selectedModelId = defaultModel?.id || models[0].id;
 		}
 
 		// Load user templates

apps/chat/apps/web/src/routes/(protected)/spaces/[id]/+page.svelte

@@ -42,7 +42,9 @@
 			// Load models
 			models = await chatService.getModels();
 			if (models.length > 0) {
-				selectedModelId = models[0].id;
+				// Find default model, or fall back to first model
+				const defaultModel = models.find((m) => m.isDefault);
+				selectedModelId = defaultModel?.id || models[0].id;
 			}
 		} catch (e) {
 			error = e instanceof Error ? e.message : 'Fehler beim Laden';