fix: Rename raw update tools and fix modular exports

Critical fix for duplicate tool names issue.

Renamed files:
- update-event.js → update-event-raw.js
- update-contact.js → update-contact-raw.js
- update-todo.js → update-todo-raw.js

Updated exports:
- updateEvent → updateEventRaw (name: 'update_event_raw')
- updateContact → updateContactRaw (name: 'update_contact_raw')
- updateTodo → updateTodoRaw (name: 'update_todo_raw')

Fixed modular structure:
- src/tools/calendar/index.js - export updateEventRaw
- src/tools/contacts/index.js - export updateContactFields + updateContactRaw
- src/tools/todos/index.js - export updateTodoFields + updateTodoRaw
- src/tools/index.js - import all field-based and raw variants

Result: 26 tools with unique names
- Field-based (PREFERRED): update_event, update_contact, update_todo
- Raw (ADVANCED): update_event_raw, update_contact_raw, update_todo_raw

Author: PhilflowIO

CHANGELOG.md

@@ -0,0 +1,42 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [2.5.2] - 2025-10-25
+
+### Fixed
+- **Issue #15**: Improved LLM robustness by adding Zod preprocessing for optional URL parameters
+  - Empty strings and common LLM placeholders ("unknown", "default", "null", etc.) are now transformed to `undefined`
+  - Affects `calendar_url` and `addressbook_url` parameters in query tools
+  - Prevents validation errors when LLMs send placeholder values instead of omitting optional parameters
+
+- **Issue #16**: Fixed `addressbook_query` tool inconsistency with other query tools
+  - Changed `addressbook_url` from required to optional parameter in inputSchema
+  - Added multi-addressbook search capability (searches all address books when URL is omitted)
+  - Updated parameter description to clarify optional nature and behavior
+  - Now consistent with `calendar_query` and `todo_query` patterns
+
+### Added
+- New helper functions: `resolveAddressBooksToSearch()` and `getAddressBookDisplayName()`
+- Comprehensive unit tests for URL preprocessing with LLM placeholder handling
+
+### Changed
+- Updated validation schemas to use new `optionalUrl` helper for better LLM compatibility
+
+## [2.5.1] - 2025-10-21
+
+### Added
+- SSE Keep-Alive heartbeats for stable connections
+- 25 MCP Tools for complete CalDAV/CardDAV/VTODO operations
+- Token optimization with PREFERRED/WARNING labels
+
+### Fixed
+- Session management improvements
+- Error handling enhancements
+
+## Previous versions
+
+See git history for changes before v2.5.1