feat: add usernames, pretty URLs, cloning, and sharing docs

## Usernames
- Add username field to User model (unique, URL-friendly)
- Add slug field to Collection model (unique per user)
- Update sign-up flow to require username with availability checking
- Create username check API endpoint

## Pretty URLs
- Add route group (profile) with pretty URL pages:
  - /{username} - User profile
  - /{username}/agents/{uid} - Agent detail
  - /{username}/agents/{uid}/chat - Chat redirect
  - /{username}/collections/{slug} - Collection detail
- Add client-side redirects from old /agents/[id] and /collections/[id] URLs

## Cloning
- Add clone API endpoints for agents and collections
- Create CloneButton component
- Add AGENT_CLONED and COLLECTION_CLONED activity types

## Documentation
- Add /docs/sharing page explaining all shareable URLs
- Document cloning functionality and visibility settings

Co-Authored-By: Claude <noreply@anthropic.com>

packages/db/prisma/schema.prisma

@@ -332,6 +332,7 @@ model User {
   email         String    @unique
   emailVerified Boolean   @default(false) @map("email_verified")
   image         String?
+  username      String?   @unique @db.VarChar(30) // URL-friendly username (nullable for migration)
 
   createdAt DateTime @default(now()) @map("created_at")
   updatedAt DateTime @updatedAt @map("updated_at")
@@ -346,6 +347,7 @@ model User {
   agentLikes      AgentLike[]
   activities      UserActivity[]
 
+  @@index([username])
   @@map("users")
 }
 
@@ -415,6 +417,7 @@ model Collection {
 
   // Collection metadata
   name        String   @db.VarChar(100)
+  slug        String?  @db.VarChar(50) // URL-friendly identifier (nullable for migration)
   description String?  @db.VarChar(500)
   isPublic    Boolean  @default(false) @map("is_public")
   likeCount   Int      @default(0) @map("like_count")
@@ -428,9 +431,10 @@ model Collection {
   agents      AgentCollection[]
   likes       CollectionLike[]
 
-  // Unique constraint: user can't have duplicate collection names
-  @@unique([userId, name])
+  // Unique constraint: user can't have duplicate collection slugs
+  @@unique([userId, slug])
   @@index([userId])
+  @@index([slug])
   @@index([isPublic])
   @@index([likeCount])
   @@index([createdAt])
@@ -726,6 +730,7 @@ enum ActivityType {
   AGENT_CREATED
   AGENT_UPDATED
   AGENT_DELETED
+  AGENT_CLONED
   AGENT_TOOL_ADDED
   AGENT_TOOL_REMOVED
   AGENT_COLLECTION_ADDED
@@ -733,6 +738,7 @@ enum ActivityType {
   COLLECTION_CREATED
   COLLECTION_UPDATED
   COLLECTION_DELETED
+  COLLECTION_CLONED
   COLLECTION_TOOL_ADDED
   COLLECTION_TOOL_REMOVED
   TOOL_LIKED

packages/db/scripts/populate-usernames-slugs.ts

@@ -0,0 +1,143 @@
+/**
+ * Migration script to populate usernames and collection slugs for existing data.
+ *
+ * Run with: pnpm --filter=@tpmjs/db tsx scripts/populate-usernames-slugs.ts
+ */
+
+import { PrismaClient } from '@prisma/client';
+
+const prisma = new PrismaClient();
+
+/**
+ * Convert a display name to a URL-friendly slug/username.
+ * - Lowercase
+ * - Replace spaces and special chars with hyphens
+ * - Remove consecutive hyphens
+ * - Trim hyphens from start/end
+ */
+function slugify(text: string): string {
+  return text
+    .toLowerCase()
+    .trim()
+    .replace(/[^\w\s-]/g, '') // Remove special chars except spaces and hyphens
+    .replace(/\s+/g, '-') // Replace spaces with hyphens
+    .replace(/-+/g, '-') // Remove consecutive hyphens
+    .replace(/^-+|-+$/g, '') // Trim hyphens from start/end
+    .slice(0, 30); // Max length for username/slug
+}
+
+/**
+ * Generate a unique username by appending a number suffix if needed.
+ */
+async function generateUniqueUsername(baseName: string): Promise<string> {
+  let username = slugify(baseName);
+
+  // If empty after slugify, use a default
+  if (!username) {
+    username = 'user';
+  }
+
+  // Check if username exists
+  const existing = await prisma.user.findUnique({ where: { username } });
+  if (!existing) {
+    return username;
+  }
+
+  // Append numbers until unique
+  let counter = 1;
+  while (true) {
+    const candidate = `${username.slice(0, 26)}-${counter}`; // Leave room for suffix
+    const exists = await prisma.user.findUnique({ where: { username: candidate } });
+    if (!exists) {
+      return candidate;
+    }
+    counter++;
+    if (counter > 1000) {
+      throw new Error(`Could not generate unique username for ${baseName}`);
+    }
+  }
+}
+
+/**
+ * Generate a unique slug for a collection within a user's scope.
+ */
+async function generateUniqueSlug(userId: string, baseName: string): Promise<string> {
+  let slug = slugify(baseName);
+
+  // If empty after slugify, use a default
+  if (!slug) {
+    slug = 'collection';
+  }
+
+  // Check if slug exists for this user
+  const existing = await prisma.collection.findFirst({
+    where: { userId, slug },
+  });
+  if (!existing) {
+    return slug;
+  }
+
+  // Append numbers until unique within user scope
+  let counter = 1;
+  while (true) {
+    const candidate = `${slug.slice(0, 46)}-${counter}`; // Leave room for suffix
+    const exists = await prisma.collection.findFirst({
+      where: { userId, slug: candidate },
+    });
+    if (!exists) {
+      return candidate;
+    }
+    counter++;
+    if (counter > 1000) {
+      throw new Error(`Could not generate unique slug for ${baseName}`);
+    }
+  }
+}
+
+async function main() {
+  console.log('🚀 Starting username and slug population...\n');
+
+  // Populate usernames for users without one
+  const usersWithoutUsername = await prisma.user.findMany({
+    where: { username: null },
+  });
+
+  console.log(`Found ${usersWithoutUsername.length} users without usernames`);
+
+  for (const user of usersWithoutUsername) {
+    const username = await generateUniqueUsername(user.name || user.email.split('@')[0]);
+    await prisma.user.update({
+      where: { id: user.id },
+      data: { username },
+    });
+    console.log(`  ✓ User "${user.name || user.email}" → @${username}`);
+  }
+
+  // Populate slugs for collections without one
+  const collectionsWithoutSlug = await prisma.collection.findMany({
+    where: { slug: null },
+    include: { user: true },
+  });
+
+  console.log(`\nFound ${collectionsWithoutSlug.length} collections without slugs`);
+
+  for (const collection of collectionsWithoutSlug) {
+    const slug = await generateUniqueSlug(collection.userId, collection.name);
+    await prisma.collection.update({
+      where: { id: collection.id },
+      data: { slug },
+    });
+    console.log(`  ✓ Collection "${collection.name}" → ${slug}`);
+  }
+
+  console.log('\n✅ Migration complete!');
+}
+
+main()
+  .catch((e) => {
+    console.error('❌ Migration failed:', e);
+    process.exit(1);
+  })
+  .finally(async () => {
+    await prisma.$disconnect();
+  });