Implement wisp: async encrypted single-retrieval file drop

Client-side libsodium encryption with the key in the URL fragment, an
Express/SQLite server holding ciphertext until a confirm-token round trip
proves successful decrypt (avoiding the delete-on-first-byte race), TTL
sweep for unclaimed drops, and a password-gated upload UI styled to match
flit. Dockerized to match the project family's conventions, with a named
volume so the DB/blobs survive redeploys, and a Gitea Actions workflow to
build and push the image.

package.json

@@ -0,0 +1,15 @@
+{
+  "name": "wisp",
+  "private": true,
+  "license": "MIT",
+  "workspaces": [
+    "client",
+    "server"
+  ],
+  "scripts": {
+    "dev": "concurrently -n client,server -c cyan,yellow \"npm run dev --workspace=client\" \"npm run dev --workspace=server\""
+  },
+  "devDependencies": {
+    "concurrently": "^8.2.2"
+  }
+}