Implement sequences feature v1.1.0

- Add -s/--sequence option to select transformation sequences
- Add -L flag to list all available sequences
- Implement 5 hardcoded sequences: default, lower, upper, minimal, utf-8
- Refactor clean_filename() to support sequence-based transformations
- Update all tests to pass sequence parameter (25 tests passing)
- Add 8 new integration tests for sequence functionality
- Update documentation (README, CHANGELOG, manpage)
- Update shell completions (bash, zsh, fish)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -5,6 +5,30 @@ 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).
 
+## [1.1.0] - 2025-02-10
+
+### Added
+- **`-s/--sequence <name>` option**: Select transformation sequence (default, lower, upper, minimal, utf-8)
+- **`-L` option**: List all available sequences (use with `-v` for details)
+- **5 hardcoded sequences**:
+  - `default`: Current behavior (umlauts→ASCII, spaces→underscores)
+  - `lower`: Like default + convert to lowercase
+  - `upper`: Like default + convert to UPPERCASE
+  - `minimal`: Only replace spaces, keep UTF-8 characters
+  - `utf-8`: UTF-8 friendly (keep umlauts, remove special chars)
+
+### Changed
+- Refactored `clean_filename()` to support sequence-based transformations
+- Umlaut replacements moved from hardcoded to sequence-specific logic
+- Case transformations now also apply to file extensions
+
+### Technical
+- Added `Sequence` struct and `CaseTransform` enum in `sanitizer.rs`
+- Extended CLI with `-s` and `-L` options
+- Added `list_sequences()` function in `main.rs`
+- Updated all unit tests to pass `Sequence` parameter
+- Added 8 new integration tests for sequence functionality
+
 ## [1.0.0] - 2025-02-10
 
 ### ⚠️ BREAKING CHANGES