Fix linting errors and remove duplicate templates/lib directory

Linting fixes:
- UP047: Use modern type parameter syntax for generic functions
- UP038/UP040: Use X | Y syntax instead of Union/tuple in type hints
- C414: Remove unnecessary list() calls in sorted()
- RUF001: Replace ambiguous unicode character with ASCII
- F841: Remove unused variable
- F821: Add missing statistics import
- W291: Remove trailing whitespace

Removed templates/lib (duplicate of templates/python/lib)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: aegeiger

client-sdks/openapi/templates/python/_types.mustache

@@ -101,7 +101,7 @@ def _validate_file_input(v: Any) -> Any:
     - tuples of (filename, content)
     """
     # If it's already bytes or str, pass through
-    if isinstance(v, (bytes, str)):
+    if isinstance(v, bytes | str):
         return v
 
     # If it's a tuple (filename, content), validate the content part

client-sdks/openapi/templates/python/_version.mustache

@@ -1,3 +1,2 @@
 __title__ = "{{packageName}}"
 __version__ = "{{packageVersion}}"
-

client-sdks/openapi/templates/python/api_client.mustache

@@ -376,7 +376,7 @@ class ApiClient:
             return tuple(
                 self.sanitize_for_serialization(sub_obj) for sub_obj in obj
             )
-        elif isinstance(obj, (datetime.datetime, datetime.date)):
+        elif isinstance(obj, datetime.datetime | datetime.date):
             return obj.isoformat()
         elif isinstance(obj, decimal.Decimal):
             return str(obj)
@@ -536,7 +536,7 @@ class ApiClient:
         for k, v in params.items() if isinstance(params, dict) else params:
             if isinstance(v, bool):
                 v = str(v).lower()
-            if isinstance(v, (int, float)):
+            if isinstance(v, int | float):
                 v = str(v)
             if isinstance(v, dict):
                 v = json.dumps(v)

client-sdks/openapi/templates/python/model_oneof.mustache

@@ -141,7 +141,7 @@ class {{classname}}({{#parent}}{{{.}}}{{/parent}}{{^parent}}BaseModel{{/parent}}
                 self.actual_instance,
                 by_alias=True,
                 exclude_none=True,
-                fallback=lambda x: x if isinstance(x, (str, int, float, bool, type(None))) else str(x)
+                fallback=lambda x: x if isinstance(x, str | int | float | bool | type(None)) else str(x)
             )
         # If it's a list of Pydantic models, serialize each one
         elif isinstance(self.actual_instance, list):
@@ -151,7 +151,7 @@ class {{classname}}({{#parent}}{{{.}}}{{/parent}}{{^parent}}BaseModel{{/parent}}
                     item,
                     by_alias=True,
                     exclude_none=True,
-                    fallback=lambda x: x if isinstance(x, (str, int, float, bool, type(None))) else str(x)
+                    fallback=lambda x: x if isinstance(x, str | int | float | bool | type(None)) else str(x)
                 )
                 if hasattr(item, '__pydantic_serializer__')
                 else item
@@ -513,7 +513,7 @@ class {{classname}}({{#parent}}{{{.}}}{{/parent}}{{^parent}}BaseModel{{/parent}}
                 self.actual_instance,
                 by_alias=True,
                 exclude_none=True,
-                fallback=lambda x: x if isinstance(x, (str, int, float, bool, type(None))) else str(x)
+                fallback=lambda x: x if isinstance(x, str | int | float | bool | type(None)) else str(x)
             )
         else:
             # primitive type

client-sdks/openapi/templates/python/rest.mustache

@@ -113,7 +113,7 @@ class RESTClientObject:
         """
         if obj is None:
             return None
-        elif isinstance(obj, (str, int, float, bool)):
+        elif isinstance(obj, str | int | float | bool):
             return obj
         elif isinstance(obj, list):
             return [self.sanitize_for_serialization(item) for item in obj]
@@ -175,7 +175,7 @@ class RESTClientObject:
 
         timeout = None
         if _request_timeout:
-            if isinstance(_request_timeout, (int, float)):
+            if isinstance(_request_timeout, int | float):
                 timeout = urllib3.Timeout(total=_request_timeout)
             elif (
                     isinstance(_request_timeout, tuple)