Preserve dark theme for existing projects

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: baremetalgo

interface/core/project_state.py

@@ -23,7 +23,7 @@ def _default_project_state(self) -> dict[str, Any]:
         return {
             "schema": "drunkenbot_ide_project",
             "version": 1,
-            "theme": "system",
+            "theme": "dark",
             "project_name": "",
             "project_dir": "",
             "paths": {

interface/core/project_state_apply.py

@@ -15,7 +15,7 @@ def _apply_project_state(self, data: dict[str, Any]) -> None:
             data: Project state loaded from JSON.
         """
 
-        self.set_theme(data.get("theme", "system"), persist=False)
+        self.set_theme(data.get("theme", "dark"), persist=False)
         self.search_box.setText(str(data.get("project_name", "")))
         paths = data.get("paths", {})
         dataset = data.get("dataset", {})

interface/theme.py

@@ -9,23 +9,24 @@
 
 SYSTEM_THEME = "system"
 DARK_THEME = "dark"
+DEFAULT_THEME = DARK_THEME
 _THEME_PROPERTY = "application_theme"
 _RECENT_PROJECTS_PATH = Path.home() / ".drunkenbot_ide" / "recent_projects.json"
 
 
 def normalize_theme(theme: object) -> str:
-    """Return a supported theme name, defaulting to the system theme."""
-    return DARK_THEME if theme == DARK_THEME else SYSTEM_THEME
+    """Return a supported theme name, defaulting to the application's Dark theme."""
+    return SYSTEM_THEME if theme == SYSTEM_THEME else DARK_THEME
 
 
 def load_startup_theme() -> str:
     """Load the theme selected for the most recently opened project."""
     try:
         recent_projects = json.loads(_RECENT_PROJECTS_PATH.read_text(encoding="utf-8"))
     except (OSError, json.JSONDecodeError):
-        return SYSTEM_THEME
+        return DEFAULT_THEME
     if not isinstance(recent_projects, list):
-        return SYSTEM_THEME
+        return DEFAULT_THEME
     for entry in recent_projects:
         if not isinstance(entry, dict):
             continue
@@ -36,13 +37,13 @@ def load_startup_theme() -> str:
             continue
         if isinstance(project_state, dict):
             return normalize_theme(project_state.get("theme"))
-    return SYSTEM_THEME
+    return DEFAULT_THEME
 
 
 def current_theme() -> str:
     """Return the QApplication theme currently in effect."""
     app = QApplication.instance()
-    return normalize_theme(app.property(_THEME_PROPERTY) if app is not None else SYSTEM_THEME)
+    return normalize_theme(app.property(_THEME_PROPERTY) if app is not None else DEFAULT_THEME)
 
 
 def apply_theme(theme: object) -> str: