P32.5 Improve notebook examples from first-user friction

[gparadis]

Parent phase issue: #191

Status: active

Goal:
Reserve a task for small docs/notebook/interface refinements that are directly motivated by first-user setup and usability friction.

Checklist:

• Triage Gloria/Camilla usability observations.
• Triage Abdulateef validation-run friction.
• Apply only focused notebook/docs/API-polish changes justified by pilot feedback.
• Keep unrelated converter compatibility work out of this phase.

Current note:
P32.1 through P32.4 are complete in commit 08186f8. This task should wait for or incorporate first-user feedback from the onboarding and validation pilot before changing notebooks or interface behavior.