Add webauthn

db/migrate/20251104042155_create_webauthn_credentials.rb

@@ -0,0 +1,32 @@
+class CreateWebauthnCredentials < ActiveRecord::Migration[8.1]
+  def change
+    create_table :webauthn_credentials do |t|
+      # Reference to the user who owns this credential
+      t.references :user, null: false, foreign_key: true, index: true
+
+      # WebAuthn specification fields
+      t.string :external_id, null: false, index: { unique: true }  # credential ID (base64)
+      t.string :public_key, null: false                             # public key (base64)
+      t.integer :sign_count, null: false, default: 0                # signature counter (clone detection)
+
+      # Metadata
+      t.string :nickname                                            # User-friendly name ("MacBook Touch ID")
+      t.string :authenticator_type                                  # "platform" or "cross-platform"
+      t.boolean :backup_eligible, default: false                    # Can be backed up (passkey sync)
+      t.boolean :backup_state, default: false                       # Currently backed up
+
+      # Tracking
+      t.datetime :last_used_at
+      t.string :last_used_ip
+      t.string :user_agent                                          # Browser/OS info
+
+      t.timestamps
+    end
+
+    # Add composite index for user-specific queries
+    add_index :webauthn_credentials, [:user_id, :external_id], unique: true
+    add_index :webauthn_credentials, [:user_id, :last_used_at]
+    add_index :webauthn_credentials, :authenticator_type
+    add_index :webauthn_credentials, :last_used_at
+  end
+end