feat: complete MVP — all 14 tasks done

- Task 13: Full documentation (README, INSTALLATION, USAGE, ARCHITECTURE)
- Task 14: Release prep (CHANGELOG, RELEASE_CHECKLIST)
- Update PROJECT_STATE.md to reflect 100% completion

CHANGELOG.md

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+# Changelog
+
+## v1.0.0 (2025-01-30)
+
+### Added
+
+- Initial release of Hostkeeper SSH/SFTP management tool
+- **Host management**: CRUD operations for SSH hosts (add, list, edit, delete)
+- **SSH connections**: Native SSH (default) and Go SSH direct mode
+- **TUI interface**: Interactive host browser using Bubble Tea
+- **Export/Import**: JSON export and import with merge/replace strategies
+- **Cross-platform builds**: Support for Linux, macOS, Windows, Termux
+- **Shell completion**: Bash, Zsh, Fish, and PowerShell support
+- **Configuration**: File-based credential storage with `0600` permissions
+- **Tag and group**: Host categorization with tags and groups
+- **Search and filter**: Filter hosts by group, tag, or text search
+
+### Commands
+
+- `hostkeeper add` — Add SSH hosts (interactive and flag-based)
+- `hostkeeper list` — List hosts with table/JSON output
+- `hostkeeper connect` — Connect to hosts with custom timeout
+- `hostkeeper edit` — Edit host configurations
+- `hostkeeper delete` — Delete hosts with confirmation
+- `hostkeeper export` — Export data to JSON
+- `hostkeeper import` — Import data with merge/replace
+- `hostkeeper tui` — Terminal user interface
+- `hostkeeper completion` — Shell completion generation
+- `hostkeeper version` — Version information
+
+### Technical
+
+- Cobra CLI framework for command structure
+- Bubble Tea TUI with keyboard navigation
+- Go SSH client for direct connections
+- Comprehensive test suite with unit and integration tests
+- Build automation via Makefile and build.sh
+
+### Notes
+
+- Initial MVP release, all core features functional
+- Encrypted storage planned for future release
+- Interactive shell in Go SSH direct mode not yet available