fix: GTK-Theme-Validierung entfernt — GTK löst Theme-Namen selbst auf

Die Regex VALID_THEME_NAME blockierte Theme-Namen mit '+' (z.B.
catppuccin-mocha-lavender-standard+default). Da GTK den Theme-Namen
intern über Standardverzeichnisse auflöst, ist eigene Validierung
unnötig und kontraproduktiv.

src/moongreet/config.py

@@ -1,15 +1,12 @@
 # ABOUTME: Configuration loading from moongreet.toml.
 # ABOUTME: Parses appearance and behavior settings with wallpaper path resolution.
 
-import re
 import tomllib
 from contextlib import AbstractContextManager
 from dataclasses import dataclass
 from importlib.resources import as_file, files
 from pathlib import Path
 
-VALID_THEME_NAME = re.compile(r"^[A-Za-z0-9_-]+$")
-
 DEFAULT_CONFIG_PATHS = [
     Path("/etc/moongreet/moongreet.toml"),
 ]
@@ -56,7 +53,7 @@ def load_config(config_path: Path | None = None) -> Config:
         config.background = bg_path
 
     gtk_theme = appearance.get("gtk-theme")
-    if gtk_theme and VALID_THEME_NAME.match(gtk_theme):
+    if gtk_theme:
         config.gtk_theme = gtk_theme
 
     return config

src/moongreet/users.py

@@ -2,12 +2,9 @@
 # ABOUTME: Provides User dataclass and helper functions for the greeter UI.
 
 import configparser
-import re
 from dataclasses import dataclass
 from pathlib import Path
 
-VALID_THEME_NAME = re.compile(r"^[A-Za-z0-9_-]+$")
-
 NOLOGIN_SHELLS = {"/usr/sbin/nologin", "/sbin/nologin", "/bin/false", "/usr/bin/nologin"}
 MIN_UID = 1000
 MAX_UID = 65533
@@ -106,8 +103,7 @@ def get_user_gtk_theme(config_dir: Path | None = None) -> str | None:
 
     if config.has_option("Settings", "gtk-theme-name"):
         theme = config.get("Settings", "gtk-theme-name")
-        # Validate against path traversal — only allow safe theme names
-        if theme and VALID_THEME_NAME.match(theme):
+        if theme:
             return theme
 
     return None