**chore: remove outdated changelog and summary documents**

- Deleted `CHANGES.md`, `CHANGES_SUMMARY.md`, `CONCURRENCY_ANALYSIS.md`, `CONCURRENCY_IMPLEMENTATION_SUMMARY.md`, and related developer documentation files.
- Removed redundant or legacy content no longer aligned with the current codebase and workflows.
- Updated repository to reflect streamlined documentation approach, reducing clutter and improving maintainability.

**Purpose**: Simplify and declutter repository by removing obsolete documentation files, ensuring it remains focused and relevant.

CHANGELOG.md

@@ -0,0 +1,76 @@
+# 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/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+### Added
+
+### Changed
+
+### Fixed
+
+## [0.26.0] - 2025-07-30
+
+### Added
+- Organized documentation structure with docs/ directory
+- Proper CHANGELOG.md for release management
+- Statistics optimizations implemented across all storage adapters
+- In-memory caching of statistics data
+- Batched updates with adaptive flush timing
+- Time-based partitioning for statistics files
+- Error handling and retry mechanisms for statistics operations
+
+### Changed
+- Moved technical documentation to docs/technical/
+- Moved development documentation to docs/development/
+- Moved guides to docs/guides/
+- Archived temporary documentation files
+- Refactored BaseStorageAdapter to include shared optimizations
+- Updated FileSystemStorage, MemoryStorage, and OPFSStorage with new statistics handling
+- Improved performance through reduced storage operations
+- Enhanced scalability with time-based partitioning
+
+### Fixed
+- Fixed FileSystemStorage constructor path operations issue where path module was used before being fully loaded
+- Deferred path operations to init() method when path module is guaranteed to be available
+- Resolved "Cannot read properties of undefined (reading 'join')" error
+
+### Technical Details
+- Added `scheduleBatchUpdate()` and `flushStatistics()` methods to BaseStorageAdapter
+- Updated core statistics methods: `saveStatistics()`, `getStatistics()`, `incrementStatistic()`, `decrementStatistic()`, and `updateHnswIndexSize()`
+- Maintained backward compatibility with legacy statistics files
+- Added fallback mechanisms for multiple storage locations
+
+## [Previous Versions]
+
+For detailed implementation notes and technical summaries of previous versions, see:
+- `docs/technical/` - Technical documentation and analysis
+- `archive/` - Archived change logs and summaries
+
+---
+
+## How to Update This Changelog
+
+When making changes to the project:
+
+1. Add new entries under `[Unreleased]` section
+2. Use the following categories:
+   - `Added` for new features
+   - `Changed` for changes in existing functionality
+   - `Deprecated` for soon-to-be removed features
+   - `Removed` for now removed features
+   - `Fixed` for any bug fixes
+   - `Security` for vulnerability fixes
+
+3. When releasing a new version:
+   - Move unreleased changes to a new version section
+   - Update the version number and date
+   - Create a new empty `[Unreleased]` section
+
+4. Link to GitHub releases: `[0.26.0] - 2025-07-28` format
+5. Keep entries concise but informative for users
+6. Include technical details in a separate subsection if needed