fix(vscode): always install palette theme extensions

programs.vscode.profiles.default.userSettings.workbench.colorTheme is
set unconditionally to the active palette's theme name (read from
themes/palettes/<theme>/apps/vscode.json), but the matching theme
extensions were bundled with devExtensions — which defaults to false.
So out of the box, VSCode silently fell back to the built-in dark
theme on every palette.

Split themeExtensions out as always-installed and devExtensions as
opt-in via nomarchy.vscode.devExtensions. themeExtensions covers the 6
palettes whose VSCode theme is packaged in nixpkgs (catppuccin,
catppuccin-latte, nord, tokyo-night, rose-pine, gruvbox).

The other 15 palettes (including the default summer-night, which uses
sainnhe.everforest) still break because their theme extensions are on
the VSCode marketplace but not yet in nixpkgs — handling that needs
pkgs.vscode-utils.extensionFromVscodeMarketplace plus per-palette
publisher/name/version/sha256 metadata. Logged separately.

features/apps/vscode.nix

@@ -7,7 +7,26 @@ let
   else
     { name = "Default Dark Modern"; };
 
-  # Development extensions that match the system theme
+  # Theme extensions matching palette vscode.json `extension` fields. Always
+  # installed because workbench.colorTheme is set unconditionally from the
+  # active palette — without the matching extension VSCode silently falls
+  # back to its default theme. Only the extensions available in
+  # pkgs.vscode-extensions are listed. Palettes whose theme extension is on
+  # the VSCode marketplace but not packaged in nixpkgs (sainnhe.everforest —
+  # affects the DEFAULT summer-night palette — plus qufiwefefwoyn.kanagawa,
+  # monokai.theme-monokai-pro-vscode, oldjobobo.*, Bjarne.*,
+  # shadesOfBuntu.flexoki-light, jovejonovski.ocean-green, TahaYVR.matteblack)
+  # still break and need pkgs.vscode-utils.extensionFromVscodeMarketplace —
+  # tracked in ROADMAP Later.
+  themeExtensions = with pkgs.vscode-extensions; [
+    catppuccin.catppuccin-vsc                  # catppuccin, catppuccin-latte
+    enkia.tokyo-night                          # tokyo-night
+    arcticicestudio.nord-visual-studio-code    # nord
+    mvllow.rose-pine                           # rose-pine
+    jdinhlife.gruvbox                          # gruvbox
+  ];
+
+  # Development extensions — opt-in via nomarchy.vscode.devExtensions.
   devExtensions = with pkgs.vscode-extensions; [
     # Language support
     ms-python.python
@@ -22,13 +41,6 @@ let
     esbenp.prettier-vscode
     dbaeumer.vscode-eslint
     bradlc.vscode-tailwindcss
-
-    # Theme extensions (provide color themes matching nomarchy palettes)
-    catppuccin.catppuccin-vsc
-    enkia.tokyo-night
-    arcticicestudio.nord-visual-studio-code
-    sainnhe.everforest
-    mvllow.rose-pine
   ];
 in
 {
@@ -51,7 +63,10 @@ in
         "editor.fontFamily" = "'${config.nomarchy.fonts.monospace}', 'Droid Sans Mono', monospace";
         "terminal.integrated.fontFamily" = config.nomarchy.fonts.monospace;
       };
-      extensions = lib.mkIf config.nomarchy.vscode.devExtensions (lib.mkDefault devExtensions);
+      extensions = lib.mkDefault (
+        themeExtensions
+        ++ lib.optionals config.nomarchy.vscode.devExtensions devExtensions
+      );
     };
   };
 }