feat: add 'Create Account' flow to login modal

- Implements a new `generate` auth provider with a no-op `login` method to bypass controller filters.
- Updates `LoginModalController.js` to intercept the `generate` provider and render an internal key generation view.
- Adds `components/login-modal.html` template for the generation flow, including key masking and copy/download actions.
- Creates `content/nostr-keys.md` documentation page and links it from the sidebar and generation view.
- Fixes a syntax error in the controller by restoring missing methods.
- Adds unit tests to verify the generation flow logic.

js/services/authProviders/generate.js

@@ -0,0 +1,10 @@
+export default {
+  id: "generate",
+  label: "Create Account",
+  description: "New to Nostr? Start here.",
+  badgeVariant: "success",
+  button: {
+    variant: "outline",
+  },
+  login: async () => {},
+};

js/services/authProviders/index.js

@@ -1,6 +1,7 @@
 import nip07 from "./nip07.js";
 import nip46 from "./nip46.js";
 import nsec from "./nsec.js";
+import generate from "./generate.js";
 
 function normalizeProviderId(provider, fallbackId) {
   if (provider && typeof provider.id === "string") {
@@ -38,7 +39,7 @@ function normalizeProviderMetadata(provider, fallbackId) {
   return Object.freeze({ id, label, description, badgeVariant });
 }
 
-const providerList = [nip07, nip46, nsec].filter(Boolean);
+const providerList = [nip07, nip46, nsec, generate].filter(Boolean);
 const providerMap = {};
 const metadataMap = {};