test(bedrock): add model picker and region routing tests

25 new tests (all Bedrock API calls mocked, no real AWS creds needed):

tests/hermes_cli/test_bedrock_model_picker.py (20 tests):
  - provider_model_ids("bedrock") uses live discovery, returns regional
    model IDs, falls back gracefully on empty/exception, resolves all
    bedrock aliases (aws, aws-bedrock, amazon-bedrock) to live discovery
  - list_authenticated_providers() section 2: bedrock appears with AWS
    creds, model list from discover_bedrock_models(), total_models
    matches, is_current flag works, absent creds hides bedrock, discovery
    failure does not crash, no duplicate entries
  - Region routing: botocore profile eu-central-1 yields eu.* model IDs
    end-to-end; env var takes priority over botocore profile
  - providers.py overlay: exists with correct transport/auth_type, label
    is non-empty, all aliases normalize to bedrock

tests/agent/test_bedrock_adapter.py (5 tests):
  - resolve_bedrock_region() botocore profile fallback, botocore failure
    fallback, us-east-1 hard fallback (with botocore mocked)

tests/agent/test_bedrock_adapter.py

@@ -117,7 +117,25 @@ class TestResolveBedrocRegion:
 
     def test_defaults_to_us_east_1(self):
         from agent.bedrock_adapter import resolve_bedrock_region
-        assert resolve_bedrock_region({}) == "us-east-1"
+        from unittest.mock import patch, MagicMock
+        mock_session = MagicMock()
+        mock_session.get_config_variable.return_value = None
+        with patch("botocore.session.get_session", return_value=mock_session):
+            assert resolve_bedrock_region({}) == "us-east-1"
+
+    def test_falls_back_to_botocore_profile_region(self):
+        from agent.bedrock_adapter import resolve_bedrock_region
+        from unittest.mock import patch, MagicMock
+        mock_session = MagicMock()
+        mock_session.get_config_variable.return_value = "eu-central-1"
+        with patch("botocore.session.get_session", return_value=mock_session):
+            assert resolve_bedrock_region({}) == "eu-central-1"
+
+    def test_botocore_failure_falls_back_to_us_east_1(self):
+        from agent.bedrock_adapter import resolve_bedrock_region
+        from unittest.mock import patch
+        with patch("botocore.session.get_session", side_effect=Exception("no botocore")):
+            assert resolve_bedrock_region({}) == "us-east-1"
 
 
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