Add README, plugin citations, and multi-platform release CI.

Ship screenshots and third-party notices for the desktop shell, and
package Windows, macOS, deb, rpm, and Flatpak from GitHub Releases.

Co-authored-by: Cursor <cursoragent@cursor.com>

src-tauri/capabilities/default.json

@@ -0,0 +1,18 @@
+{
+  "$schema": "../gen/schemas/desktop-schema.json",
+  "identifier": "default",
+  "description": "Main window, including the embedded dsh WebUI",
+  "windows": ["main"],
+  "remote": {
+    "urls": ["http://127.0.0.1:*", "http://localhost:*"]
+  },
+  "permissions": [
+    "core:default",
+    "core:window:allow-close",
+    "core:window:allow-minimize",
+    "core:window:allow-toggle-maximize",
+    "core:window:allow-start-dragging",
+    "core:webview:allow-internal-toggle-devtools",
+    "opener:default"
+  ]
+}