fix(ai-chat): drop redundant "(free)" suffix from OpenRouter model names

OpenRouter appends "(free)" to the display name of its free-tier model
variants (e.g. "Liquid AI: LFM2.5-2.6B (free)"). The ":free" model id
already conveys this, so the suffix is redundant in the human-facing
name shown across Puter and the developer docs.

Strip a trailing "(free)" from the coerced display name while keeping
the original name as an alias so existing references still resolve.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018q5AWeB6pvt3LPHYxknis6

src/backend/drivers/ai-chat/providers/openrouter/OpenRouterProvider.ts

@@ -268,12 +268,17 @@ export class OpenRouterProvider implements IChatProvider {
             if (!microcentCosts.request) {
                 microcentCosts.request = 0;
             }
+            // OpenRouter appends "(free)" to the display name of its free-tier
+            // model variants. The ":free" model id already conveys that, so
+            // drop the redundant suffix from the human-facing name.
+            const displayName = model.name.replace(/\s*\(free\)\s*$/i, '');
             coerced_models.push({
                 id: `openrouter:${model.id}`,
-                name: `${model.name} (OpenRouter)`,
+                name: `${displayName} (OpenRouter)`,
                 aliases: [
                     model.id,
                     model.name,
+                    displayName,
                     `openrouter/${model.id}`,
                     model.id.split('/').slice(1).join('/'),
                 ],