* refactor(core): replace text truncation utilities with new marker system
- Remove old truncate_text_utils module and its exports
- Replace TRUNCATION_MARKER_START with _TRUNCATION_NOTICE_MARKER constant
- Update as_msg_stat.py to split content using new marker format
- Modify FileIO tool to use TRUNCATION_NOTICE_MARKER for continuation hints
- Change is_truncated function checks to use marker presence detection
- Move transformers dependency from main deps to light extra dependencies
- Update tool result compactor tests to verify marker instead of is_truncated calls
* feat(file_io): enhance file operations with path resolution and append functionality
- Add expanduser() to resolve file paths with ~ symbol
- Implement proper file existence and type validation in update_file
- Add new append_file method to append content to files
- Update truncation notice format for better readability
- Fix typo in error message from "provide" to "provided"
- Update transformers dependency in pyproject.toml
- Remove duplicate transformers dependency from light extras
* refactor(file_io): disable pylint too-many-return-statements warning
* perf(file_watcher): increase default polling delay and optimize watcher configuration
- Increased default poll_delay_ms from 1000ms to 2000ms to reduce CPU usage
- Removed force_polling parameter as it's no longer needed with updated polling strategy
- Simplified async watch configuration by removing conditional force_polling logic
- Reduced overall system resource consumption during file watching operations
* refactor(memory): update conversation log documentation in memory summary
- Changed "Raw conversation logs" to "Earlier conversation logs" for clarity
- Added warning note about potentially large dialog file sizes
- Improved formatting with additional line break for better readability
- Maintained existing compressed summary integration unchanged
* feat(memory): add long-term memory support to file-based memory system
- Initialize _long_term_memory attribute as empty string
- Add memories section to content when long-term memory exists
- Consolidate summary and memories into single user message
- Format memories with markdown header # Memories
- Maintain existing compressed summary functionality
- Join multiple content parts with double newlines
