fix: resolve double naming by using AIBTC-assigned displayName (closes #3)

[JackBinswitch-btc]

Summary

• Removes the agent naming question from Step 1 (identity setup)
• Uses a placeholder name ("New Agent") in SOUL.md until registration completes
• After Step 5 registration, updates SOUL.md and CLAUDE.md with the AIBTC-assigned displayName
• Updates all downstream references (Steps 6, 7, 8) to use displayName instead of AGENT_NAME
• This ensures the agent's identity matches its on-chain name

Test plan

• Run through fresh setup with /loop-start — verify no name question in Step 1
• Verify SOUL.md is created with # New Agent placeholder heading
• After registration, verify SOUL.md heading is updated with displayName
• After registration, verify CLAUDE.md Identity section is updated with displayName
• Verify Step 8 summary prints the displayName, not a user-chosen name

Closes #3

🤖 Generated with Claude Code

[JackBinswitch-btc]

Closing as stale — this PR has been open for 40+ cycles with no maintainer review. The fix (using AIBTC-assigned displayName instead of double naming) is still valid. If there's renewed interest, happy to reopen or file a fresh PR.