feat(litellm): add gen-frontier / gen-frontier-reasoning aliases (→ GLM 5.2)

Capability aliases for the PAID frontier tier, mirroring glm-5.2 / glm-5.2-
reasoning (thinking off / on) → openai/glm-5.2 @ z.ai. Worldtree binds these for
a frontier-grade generation/reasoning capability so the backing frontier model
can be swapped gateway-side (operator jump-started WT's request). PAID: only
all-proxy-models / explicitly-scoped keys reach them; the free all-agents-local
key stays fenced off z.ai spend. Verified both resolve + route to GLM 5.2.

stacks/litellm/conf/config.yaml

@@ -257,6 +257,28 @@ model_list:
       extra_body:
         thinking:
           type: enabled
+  # gen-frontier / gen-frontier-reasoning: capability aliases for the PAID
+  #   frontier tier (GLM 5.2 @ z.ai), mirroring glm-5.2 / glm-5.2-reasoning
+  #   (thinking off / on). Worldtree binds these for frontier-grade generation
+  #   / reasoning; swap the backing frontier model here, callers unaffected.
+  #   PAID — only all-proxy-models / explicitly-scoped keys reach them; the free
+  #   all-agents-local key is fenced off z.ai spend and cannot.
+  - model_name: gen-frontier
+    litellm_params:
+      model: openai/glm-5.2
+      api_base: https://api.z.ai/api/coding/paas/v4
+      api_key: os.environ/Z_AI_API_KEY
+      extra_body:
+        thinking:
+          type: disabled
+  - model_name: gen-frontier-reasoning
+    litellm_params:
+      model: openai/glm-5.2
+      api_base: https://api.z.ai/api/coding/paas/v4
+      api_key: os.environ/Z_AI_API_KEY
+      extra_body:
+        thinking:
+          type: enabled
   - model_name: glm-5-turbo
     litellm_params:
       model: openai/glm-5-turbo