Summary

Adds --single-user flag for personal/mobile deployments where only one user needs access to the pod.

Closes #76

Changes

• config.js: Added singleUser and singleUserName options
• bin/jss.js: Added --single-user and --single-user-name CLI flags
• server.js: Auto-creates pod on startup in single-user mode
• idp/index.js: Disables registration endpoint in single-user mode

Usage

# Basic single-user mode (creates pod at /me/)
jss start --single-user --idp

# Custom username
jss start --single-user --single-user-name alice --idp

# Via environment
JSS_SINGLE_USER=true jss start --idp

Features

• Pod auto-created on first startup with full structure (inbox, public, private, profile, Settings)
• Registration endpoint returns 403 with friendly "Registration Disabled" page
• Login still works for the single user
• Works with sandymount: sandymount start --single-user

Test Plan

• Pod created automatically on startup
• Registration page shows "Registration Disabled"
• Login still accessible
• Profile accessible at /me/profile/card
• Console shows "Single-user: me (registration disabled)"