fix: pass email via --email flag in kalibr prompt --openclaw, remove ask-user step

[devonakelley]

Problem

Step 2 of OPENCLAW_PROMPT_TEXT told the agent to ask the user for their email. The onboarding flow already has the email — the agent should never ask.

Fix

• Added --email option to kalibr prompt --openclaw
• When --email is provided, step 2 uses the email directly: kalibr auth --agent --email user@example.com
• When no --email is provided, step 2 shows a clean placeholder: kalibr auth --agent --email <YOUR_EMAIL>
• Removed all 'Ask the user' language from OPENCLAW_PROMPT_TEXT
• Updated README to show both usage patterns

Usage

# Website-driven (email pre-filled, zero human steps):
kalibr prompt --openclaw --email user@example.com

# Manual (user fills in email themselves):
kalibr prompt --openclaw