Look up or estimate a battery charger's output specs from a free-text description (AI)

Used by the wireframe editor's add-charger dialog. Calls the external OpenRouter chat-completions API (https://openrouter.ai) with the model configured server-side in OPENROUTER_CHARGER_ASSISTANT_MODEL, falling back to OPENROUTER_LOAD_ASSISTANT_MODEL; 20 s timeout. The optional power-source context sharpens the estimate. 20 requests per hour per client IP (counted separately from /api/loads/estimate). The client IP is the first X-Forwarded-For entry, else X-Real-IP, else one shared unknown bucket; counters are kept in memory per server instance and per route. No CORS headers.