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>

man/ntu.1

@@ -1,4 +1,4 @@
-.TH NTU 1 "2025-02-10" "NameToUnix 1.0.0" "User Commands"
+.TH NTU 1 "2025-02-10" "NameToUnix 1.1.0" "User Commands"
 .SH NAME
 ntu \- sanitize file and directory names to Unix conventions
 .SH SYNOPSIS
@@ -21,6 +21,12 @@ like .tar.gz, and handles hidden files correctly.
 .BR \-r ", " \-\-recursive
 Process directories recursively (default: only immediate children)
 .TP
+.BR \-s ", " \-\-sequence " \fINAME\fR"
+Use a specific transformation sequence. Available sequences: default, lower, upper, minimal, utf-8. Use \fB\-L\fR to list all sequences.
+.TP
+.BR \-L
+List all available transformation sequences. Use with \fB\-v\fR for detailed information.
+.TP
 .BR \-\-conf " \fIFILE\fR"
 Use a specific configuration file instead of the default hierarchy
 .TP
@@ -78,6 +84,27 @@ Replaced with underscores.
 .TP
 .B Multiple Underscores
 Consecutive underscores are collapsed to a single underscore.
+.SH SEQUENCES
+.B ntu
+supports different transformation sequences that can be selected with the \fB\-s\fR option:
+.TP
+.B default
+Standard transformation: spaces become underscores, German umlauts are converted
+to ASCII equivalents, special characters are removed or replaced.
+.TP
+.B lower
+Like default, but converts all text to lowercase.
+.TP
+.B upper
+Like default, but converts all text to UPPERCASE.
+.TP
+.B minimal
+Minimal changes: only replaces spaces with underscores, keeps umlauts and
+other UTF-8 characters.
+.TP
+.B utf-8
+UTF-8 friendly: keeps umlauts and UTF-8 characters, replaces spaces,
+removes special characters.
 .SH EXCLUDED PATTERNS
 By default, the following directories are automatically excluded:
 .PP
@@ -111,6 +138,21 @@ Process multiple directories:
 .TP
 Verbose output with no colors:
 .B ntu \-v \-\-no\-color /path/to/directory
+.TP
+Use lowercase sequence:
+.B ntu \-r \-s lower /path/to/files
+.TP
+Minimal mode (only spaces, keep UTF-8):
+.B ntu \-s minimal /path/to/files
+.TP
+UTF-8 friendly mode:
+.B ntu \-s utf-8 /path/to/files
+.TP
+List all available sequences:
+.B ntu \-L
+.TP
+List sequences with details:
+.B ntu \-L \-v
 .SH CONFIGURATION
 .B ntu
 looks for configuration files in the following locations (in order):