Vignette: orientation + how to use betydata (offline-first)

[dlebauer]

Goal

• Provide a short “start here” vignette that orients a new user to what’s in the package and how to use it offline.

Tasks

• Add a vignette (e.g. vignettes/orientation.Rmd or .qmd) that:
  • installs/loads betydata
  • lists available datasets (exported objects)
  • shows basic exploration:
    • head(traitsview)
    • count(traitsview, trait)
    • filtering by checked
  • explains (briefly) that all examples are offline-only and do not require Postgres/API
  • points users to the other vignettes (manuscript, SQL analogs, dplyr analogs, PFTs, priors)

Acceptance criteria

• Vignette builds under R CMD check.
• A new user can copy/paste examples and immediately get meaningful output.

Non-goals

• No long narrative documentation; keep it lean and practical.