Fix GitHub Actions functional test env var conflict

Fixed the functional test failure by removing MODEL_ENDPOINT_0 from
the functional test step in GitHub Actions workflow.

The functional test test_initialize_model_map_with_env_vars sets its
own test endpoints (MODEL_ENDPOINT_1, MODEL_ENDPOINT_2) and was failing
because MODEL_ENDPOINT_0 from the workflow was interfering.

Changes:
- .github/workflows/test.yml: Removed MODEL_ENDPOINT_0 from functional test step
- .github/workflows/test.yml: Updated unit/integration tests to use hermes.ai.unturf.com
- tests/functional/test_guarded_ai.py: Fixed patch.dict to use clear=False

Unit and integration tests still have MODEL_ENDPOINT_0 configured
since they need it for app initialization. Functional tests now run
without env var interference and can test their own endpoint configs.

All 46 functional tests pass locally.

.github/workflows/test.yml

@@ -37,8 +37,8 @@ jobs:
       env:
         SQLALCHEMY_DATABASE_URI: "sqlite:///:memory:"
         TESTING: "1"
-        MODEL_ENDPOINT_0: "https://test.api"
-        MODEL_API_KEY_0: "test-key"
+        MODEL_ENDPOINT_0: "https://hermes.ai.unturf.com/v1"
+        MODEL_API_KEY_0: "dummy"
 
     - name: Run functional tests
       run: |
@@ -46,8 +46,6 @@ jobs:
       env:
         SQLALCHEMY_DATABASE_URI: "sqlite:///:memory:"
         TESTING: "1"
-        MODEL_ENDPOINT_0: "https://test.api"
-        MODEL_API_KEY_0: "test-key"
 
     - name: Run integration tests
       run: |
@@ -55,8 +53,8 @@ jobs:
       env:
         SQLALCHEMY_DATABASE_URI: "sqlite:///:memory:"
         TESTING: "1"
-        MODEL_ENDPOINT_0: "https://test.api"
-        MODEL_API_KEY_0: "test-key"
+        MODEL_ENDPOINT_0: "https://hermes.ai.unturf.com/v1"
+        MODEL_API_KEY_0: "dummy"
 
     - name: Validate activity YAML files
       run: |