Demo app, collections/features CRUD, QR codes, docs

Demo app (web/):
- Collections: select, rename, remove (x button per row), delete
- Features: add point (lon/lat validation), remove, list in selected collection
- QR codes for pk (private) and pb (public) keys
- Restore public key from private key
- 409 Conflict handled for already-registered login
- Title: Momswap Geo Backend Use-Cases Test

Backend:
- PATCH /v1/collections/{id} for rename
- DELETE /v1/collections/{id}
- Clearer lon/lat validation errors (-180..180, -90..90)

Client:
- updateCollection, deleteCollection, derivePublicKey

Docs:
- docs/frontend-development.md (demo app, local dev)
- README links to all docs

Made-with: Cursor

libs/geo-api-client/dist/index.js

@@ -470,6 +470,11 @@ async function generateKeyPair() {
     privateKey: bytesToBase64Url(privateKey)
   };
 }
+async function getPublicKeyFromPrivate(privateKeyBase64) {
+  const privateKey = base64UrlToBytes(privateKeyBase64);
+  const publicKey = await getPublicKeyAsync(privateKey);
+  return bytesToBase64Url(publicKey);
+}
 async function signMessage(privateKeyBase64, message) {
   const privateKey = base64UrlToBytes(privateKeyBase64);
   const signature = await signAsync(textToBytes(message), privateKey);
@@ -519,6 +524,9 @@ class GeoApiClient {
   getStoredKeys() {
     return loadKeys(this.storage, this.storageKey);
   }
+  async derivePublicKey(privateKey) {
+    return getPublicKeyFromPrivate(privateKey);
+  }
   importKeys(keys) {
     saveKeys(this.storage, keys, this.storageKey);
   }
@@ -538,7 +546,9 @@ class GeoApiClient {
     const res = await fetch(`${this.baseUrl}${path}`, { ...init, headers, body });
     if (!res.ok) {
       const maybeJson = await res.json().catch(() => ({}));
-      const msg = maybeJson.error ?? `HTTP ${res.status}`;
+      let msg = maybeJson.error ?? `HTTP ${res.status}`;
+      if (maybeJson.hint)
+        msg += `. ${maybeJson.hint}`;
       throw new Error(msg);
     }
     if (res.status === 204) {
@@ -604,6 +614,15 @@ class GeoApiClient {
   async createCollection(name) {
     return this.request("/v1/collections", { method: "POST", body: { name } });
   }
+  async updateCollection(collectionId, name) {
+    return this.request(`/v1/collections/${collectionId}`, {
+      method: "PATCH",
+      body: { name }
+    });
+  }
+  async deleteCollection(collectionId) {
+    return this.request(`/v1/collections/${collectionId}`, { method: "DELETE" });
+  }
   async listFeatures(collectionId) {
     return this.request(`/v1/collections/${collectionId}/features`, { method: "GET" });
   }
@@ -616,11 +635,15 @@ class GeoApiClient {
       }
     });
   }
+  async deleteFeature(featureId) {
+    return this.request(`/v1/features/${featureId}`, { method: "DELETE" });
+  }
 }
 export {
   signMessage,
   saveKeys,
   loadKeys,
+  getPublicKeyFromPrivate,
   generateKeyPair,
   clearKeys,
   GeoApiClient,