Add Forgejo theme and homepage

themes/theme-forgejo-dark.css

@@ -0,0 +1,25 @@
+/*
+ * theme-forgejo-dark.css (custom override)
+ * ─────────────────────────────────────────────────────────────────────────
+ * The built-in Forgejo dark palette, snapshotted as _base-forgejo-dark.css,
+ * plus the shared neumorphic/soft-UI layer.
+ *
+ * Note: this overrides the built-in theme of the same name so the soft look
+ * applies to anyone who picked "forgejo-dark". The palette is frozen from
+ * Forgejo 15.0.0; update _base-forgejo-dark.css if you upgrade Forgejo and
+ * want newer built-in colours.
+ */
+
+@import url("./_base-forgejo-dark.css");
+@import url("./theme-neumorphism.css");
+
+:root {
+  color-scheme: dark;
+  --is-dark-theme: true;
+
+  --nm-shadow-dark: rgba(0, 0, 0, 0.62);
+  --nm-shadow-light: rgba(255, 255, 255, 0.05);
+  --nm-divider-color: rgba(255, 255, 255, 0.07);
+  --nm-radius: 14px;
+  --nm-radius-sm: 10px;
+}