v1.8.2 — Username Preferences (Professional/Casual)

Stores 6 preferred usernames in keychain — 3 professional, 3 casual — each with primary/secondary/tertiary priority.

When signing up for a new service, the agent:

1. Detects context (professional for GitHub/Vercel/AWS, casual for everything else)
2. Tries primary username → secondary → tertiary
3. Only appends a short number if all three are taken
4. Never generates random usernames like rishi-2160504210

Asked once on first signup, stored forever. Works cross-platform via keychain.sh.