test: 13 Integration-Tests hinzugefügt + .gitignore optimiert

Integration-Tests:
- test_help_flag, test_version_flag
- test_dry_run_no_changes, test_actual_rename
- test_hidden_files_preserved, test_hidden_file_with_spaces
- test_umlaut_conversion, test_double_extension
- test_exclude_pattern, test_quiet_mode
- test_multiple_paths, test_parentheses_removed
- test_special_identifiers_preserved

.gitignore:
- Besser organisiert (Kategorien)
- Cargo.lock hinzugefügt
- Temporäre Dateien (*.tmp, *.log, *.bak)
- OS-spezifische Dateien (Thumbs.db)
- Test-Artefakte

Gesamt: 22 Tests (9 Unit + 13 Integration)

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

Cargo.lock

@@ -7,6 +7,7 @@ name = "NameToUnix"
 version = "0.2.0"
 dependencies = [
  "anyhow",
+ "assert_cmd",
  "assert_fs",
  "clap",
  "dirs",
@@ -93,6 +94,21 @@ version = "1.0.97"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dcfed56ad506cb2c684a14971b8861fdc3baaaae314b9e5f9bb532cbe3ba7a4f"
 
+[[package]]
+name = "assert_cmd"
+version = "2.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c5bcfa8749ac45dd12cb11055aeeb6b27a3895560d60d71e3c23bf979e60514"
+dependencies = [
+ "anstyle",
+ "bstr",
+ "libc",
+ "predicates",
+ "predicates-core",
+ "predicates-tree",
+ "wait-timeout",
+]
+
 [[package]]
 name = "assert_fs"
 version = "1.1.2"
@@ -127,6 +143,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "531a9155a481e2ee699d4f98f43c0ca4ff8ee1bfd55c31e9e98fb29d2b176fe0"
 dependencies = [
  "memchr",
+ "regex-automata",
  "serde",
 ]
 
@@ -840,6 +857,15 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "06abde3611657adf66d383f00b093d7faecc7fa57071cce2578660c9f1010821"
 
+[[package]]
+name = "wait-timeout"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09ac3b126d3914f9849036f826e054cbabdc8519970b8998ddaf3b5bd3c65f11"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "walkdir"
 version = "2.5.0"