feat(onboarding): tighten setup copy from demo feedback
Commit

- Consent prompt lists the missing steps as terse bullets under the checklist's own 'N steps left' heading instead of one run-on sentence.
- Step-by-step confirms ask the action ('Log in?', 'Mirror this repo?') instead of reusing checklist row labels ('Logged in' + Yes/No).
- Login copy no longer claims a web login or promises a browser — the step authenticates the CLI; headless terminals use a device code.
- Import prompts drop 'into Entire' and say 'stored locally': imported sessions live in local git refs and entire session list, not entire.io.
- The fully-connected line carries the repo's entire.io overview link (Connected: user · https://entire.io/gh/o/r) instead of 'mirrored to <slug>'; expertsWebBaseURL renamed to webBaseURL for shared use.
Co-Authored-By: Claude Fable 5 noreply@anthropic.com Entire-Checkpoint: 01KXPCWKWNGG7HVJEXP7ZF70JY
Checkpoints
Checkpoint 1