Add encrypted key support for chat and nodes

Introduces encrypted private key storage for nodes and users, updates chat message schema to support sender-side encryption, and adds supporting libraries and tests for cryptographic signing and identity unlock flows. Includes new database migrations, API route updates, and React components for identity unlock prompts.

src/lib/api/signed-fetch.ts

@@ -0,0 +1,159 @@
+/**
+ * Signed Fetch - Client-side API wrapper
+ * 
+ * Automatically signs all user actions with their private key before
+ * sending to the server. This ensures cryptographic proof of authenticity.
+ */
+
+import { createSignedAction, hasUserPrivateKey } from '@/lib/crypto/user-signing';
+
+export interface SignedFetchOptions {
+  method?: string;
+  body?: any;
+  headers?: Record<string, string>;
+}
+
+/**
+ * Make a signed API request
+ * 
+ * @param url - The API endpoint
+ * @param action - The action being performed (e.g., 'like', 'follow', 'post')
+ * @param data - The action data
+ * @param userDid - The user's DID
+ * @param userHandle - The user's handle
+ * @param options - Additional fetch options
+ */
+export async function signedFetch(
+  url: string,
+  action: string,
+  data: any,
+  userDid: string,
+  userHandle: string,
+  options: SignedFetchOptions = {}
+): Promise<Response> {
+  // Check if user has their private key loaded
+  if (!hasUserPrivateKey()) {
+    throw new Error('User identity not unlocked. Please log in again.');
+  }
+
+  // Create signed action
+  // Note: createSignedAction now generates nonce and ts internally
+  const signedAction = await createSignedAction(action, data, userDid, userHandle);
+
+  // Make the request
+  return fetch(url, {
+    method: options.method || 'POST',
+    headers: {
+      'Content-Type': 'application/json',
+      ...options.headers,
+    },
+    body: JSON.stringify(signedAction),
+  });
+}
+
+/**
+ * Helper for common actions
+ */
+export const signedAPI = {
+  /**
+   * Like a post
+   */
+  async likePost(postId: string, userDid: string, userHandle: string) {
+    return signedFetch(
+      `/api/posts/${postId}/like`,
+      'like',
+      { postId },
+      userDid,
+      userHandle
+    );
+  },
+
+  /**
+   * Unlike a post
+   */
+  async unlikePost(postId: string, userDid: string, userHandle: string) {
+    return signedFetch(
+      `/api/posts/${postId}/like`,
+      'unlike',
+      { postId },
+      userDid,
+      userHandle,
+      { method: 'DELETE' }
+    );
+  },
+
+  /**
+   * Follow a user
+   */
+  async followUser(targetHandle: string, userDid: string, userHandle: string) {
+    return signedFetch(
+      `/api/users/${targetHandle}/follow`,
+      'follow',
+      { targetHandle },
+      userDid,
+      userHandle
+    );
+  },
+
+  /**
+   * Unfollow a user
+   */
+  async unfollowUser(targetHandle: string, userDid: string, userHandle: string) {
+    return signedFetch(
+      `/api/users/${targetHandle}/follow`,
+      'unfollow',
+      { targetHandle },
+      userDid,
+      userHandle,
+      { method: 'DELETE' }
+    );
+  },
+
+  /**
+   * Create a post
+   */
+  async createPost(
+    content: string,
+    mediaIds: string[],
+    linkPreview: any,
+    replyToId: string | undefined,
+    isNsfw: boolean,
+    userDid: string,
+    userHandle: string
+  ) {
+    return signedFetch(
+      '/api/posts',
+      'post',
+      { content, mediaIds, linkPreview, replyToId, isNsfw },
+      userDid,
+      userHandle
+    );
+  },
+
+  /**
+   * Repost a post
+   */
+  async repostPost(postId: string, userDid: string, userHandle: string) {
+    return signedFetch(
+      `/api/posts/${postId}/repost`,
+      'repost',
+      { postId },
+      userDid,
+      userHandle
+    );
+  },
+
+  /**
+   * Unrepost a post
+   */
+  async unrepostPost(postId: string, userDid: string, userHandle: string) {
+    return signedFetch(
+      `/api/posts/${postId}/repost`,
+      'unrepost',
+      { postId },
+      userDid,
+      userHandle,
+      { method: 'DELETE' }
+    );
+  },
+};