Fix settings export: custom themes now travel with their full palette, fonts stay name-only

Core.py

@@ -459,8 +459,24 @@ def ExportSettings(Config: AppConfig, DestPath: Path) -> None:
     file... applies to every other SaraSuite program"). A future SaraView/
     SaraTag/etc. import would read the same [SaraSuite] section plus its
     own top-level one, ignoring [SaraFem] — the same convention
-    ImportSettings below uses to ignore sections that aren't its own."""
-    Data = {"SaraSuite": asdict(_OwnSettings(Config)), "SaraFem": asdict(Config)}
+    ImportSettings below uses to ignore sections that aren't its own.
+
+    A custom (non-built-in) theme's actual palette rides along under
+    ThemeData (Bugs/Major: "Cannot export custom theme... theme can be
+    fully exported") — a theme is just a small local TOML file, nothing
+    stops it traveling with the export, unlike a font, which stays a name
+    only (the font itself needs installing some other way regardless of
+    what this file says)."""
+    OwnSettings = _OwnSettings(Config)
+    SharedData = asdict(OwnSettings)
+    if OwnSettings.Theme not in BuiltinThemes:
+        ThemeFile = ThemesDir / f"{OwnSettings.Theme}.toml"
+        if ThemeFile.exists():
+            try:
+                SharedData["ThemeData"] = toml.loads(ThemeFile.read_text()).get("Palette", {})
+            except toml.TomlDecodeError:
+                pass
+    Data = {"SaraSuite": SharedData, "SaraFem": asdict(Config)}
     DestPath.write_text(toml.dumps(Data))
 
 
@@ -478,10 +494,20 @@ def ImportSettings(Config: AppConfig, SrcPath: Path) -> None:
 
     SharedData = Data.get("SaraSuite")
     if isinstance(SharedData, dict):
+        # Popped before the known-fields filter below (same reason as the
+        # SaraTag/SaraSortd/FolderIconBands nested data elsewhere here) —
+        # ThemeData isn't a SharedSettings field, it's the custom theme's
+        # actual palette, written out as that theme's own local file so the
+        # name being imported alongside it actually resolves to something.
+        ThemeData = SharedData.pop("ThemeData", None)
         KnownSharedFields = {F for F in SharedSettings.__dataclass_fields__}
         Filtered = {K: V for K, V in SharedData.items() if K in KnownSharedFields}
         Merged = asdict(_OwnSettings(Config))
         Merged.update(Filtered)
+        ImportedTheme = Merged.get("Theme")
+        if isinstance(ThemeData, dict) and ImportedTheme and ImportedTheme not in BuiltinThemes:
+            ThemesDir.mkdir(parents=True, exist_ok=True)
+            (ThemesDir / f"{ImportedTheme}.toml").write_text(toml.dumps({"Palette": ThemeData}))
         SharedSettings(**Merged).Save()
 
     OwnData = Data.get("SaraFem")