fix: respect OPENAI_BASE_URL when resolving API key priority

When base_url points to a non-OpenRouter endpoint (e.g. Z.ai),
OPENROUTER_API_KEY incorrectly takes priority over OPENAI_API_KEY,
sending the wrong credentials. This causes 401 errors on the main
inference path and forces users to comment out OPENROUTER_API_KEY,
which then breaks auxiliary clients (compression, vision).

Fix: check whether base_url contains "openrouter" and swap the key
priority accordingly. Also adds GLM-4.7 and GLM-5 context lengths
to DEFAULT_CONTEXT_LENGTHS.

agent/model_metadata.py

@@ -33,6 +33,8 @@ DEFAULT_CONTEXT_LENGTHS = {
     "meta-llama/llama-3.3-70b-instruct": 131072,
     "deepseek/deepseek-chat-v3": 65536,
     "qwen/qwen-2.5-72b-instruct": 32768,
+    "glm-4.7": 202752,
+    "glm-5": 202752,
 }