Iteratively plans a France Schengen trip with the user — destinations,
dates, duration, group composition, rough budget — and surfaces the
consular-credibility checks that will affect the visa application
later. Outputs a trip skeleton that downstream skills
(/itinerary-builder, /document-checklist, /cost-estimate) can consume.
Use when the user says "help me plan a trip to France", "I want to go
to Europe but don't know where", "we want a Schengen trip but need to
figure out details", or starts with a vague idea instead of fixed
dates. (Schengen-master skills)
