Updated package loch and added changeset file

Author: CalebGerman

.changeset/lovely-pots-feel.md

@@ -0,0 +1,32 @@
+---
+"@itwin/access-control-client": major
+---
+
+Complete API redesign with enhanced TypeScript support and new functionality
+
+BREAKING CHANGES:
+
+- Renamed AccessControlAPIResponse<T> → BentleyAPIResponse<T>
+- Renamed Error → ApimError (avoids JS built-in conflict)
+- Removed 'Async' suffix from all method names (e.g., getITwinRolesAsync → getITwinRoles)
+- Converted all enums to string union types for better tree shaking
+- Response structure: Direct arrays/objects → wrapped responses with HAL links
+- Query parameters: AccessControlQueryArg → ODataQueryParams with OData v4 support
+
+NEW FEATURES:
+
+- iTwin Shares client with complete CRUD operations
+- Group Member Invitations client for invitation management
+- Enhanced type safety with conditional types for result modes
+- HAL specification compliance with _links navigation
+- Advanced mapped types for handling missing users in member responses
+
+TECHNICAL IMPROVEMENTS:
+
+- String unions over enums (zero runtime overhead, better tree shaking)
+- Conditional types for type-safe result modes
+- Self-documenting response wrappers with descriptive property names
+- Reorganized type system into dedicated files under src/types/
+- Enhanced error handling with proper null/undefined type safety
+
+See MIGRATION-GUIDE-v3-to-v4.md for complete migration instructions.