Rename express/ to backend/ and update references

Update paths in sync.sh, master/main.go, and CLAUDE.md to reflect
the directory rename.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/generated/db.d.ts

@@ -0,0 +1,109 @@
+/**
+ * This file was generated by kysely-codegen.
+ * Please do not edit it manually.
+ */
+
+import type { ColumnType } from "kysely";
+
+export type Generated<T> =
+    T extends ColumnType<infer S, infer I, infer U>
+        ? ColumnType<S, I | undefined, U>
+        : ColumnType<T, T | undefined, T>;
+
+export type Timestamp = ColumnType<Date, Date | string, Date | string>;
+
+export interface _Migrations {
+    applied_at: Generated<Timestamp>;
+    id: Generated<number>;
+    name: string;
+}
+
+export interface Capabilities {
+    description: string | null;
+    id: string;
+    name: string;
+}
+
+export interface Groups {
+    created_at: Generated<Timestamp>;
+    id: string;
+    name: string;
+}
+
+export interface RoleCapabilities {
+    capability_id: string;
+    granted_at: Generated<Timestamp>;
+    revoked_at: Timestamp | null;
+    role_id: string;
+}
+
+export interface Roles {
+    description: string | null;
+    id: string;
+    name: string;
+}
+
+export interface Sessions {
+    auth_method: string;
+    created_at: Generated<Timestamp>;
+    expires_at: Timestamp;
+    id: Generated<string>;
+    ip_address: string | null;
+    is_used: Generated<boolean | null>;
+    revoked_at: Timestamp | null;
+    token_hash: string;
+    token_type: string;
+    user_agent: string | null;
+    user_email_id: string | null;
+    user_id: string;
+}
+
+export interface UserCredentials {
+    created_at: Generated<Timestamp>;
+    credential_type: Generated<string>;
+    id: string;
+    password_hash: string | null;
+    updated_at: Generated<Timestamp>;
+    user_id: string;
+}
+
+export interface UserEmails {
+    created_at: Generated<Timestamp>;
+    email: string;
+    id: string;
+    is_primary: Generated<boolean>;
+    is_verified: Generated<boolean>;
+    normalized_email: string;
+    revoked_at: Timestamp | null;
+    user_id: string;
+    verified_at: Timestamp | null;
+}
+
+export interface UserGroupRoles {
+    granted_at: Generated<Timestamp>;
+    group_id: string;
+    revoked_at: Timestamp | null;
+    role_id: string;
+    user_id: string;
+}
+
+export interface Users {
+    created_at: Generated<Timestamp>;
+    display_name: string | null;
+    id: string;
+    status: Generated<string>;
+    updated_at: Generated<Timestamp>;
+}
+
+export interface DB {
+    _migrations: _Migrations;
+    capabilities: Capabilities;
+    groups: Groups;
+    role_capabilities: RoleCapabilities;
+    roles: Roles;
+    sessions: Sessions;
+    user_credentials: UserCredentials;
+    user_emails: UserEmails;
+    user_group_roles: UserGroupRoles;
+    users: Users;
+}