Document vignette workflow in README, add latest example results

Add example results output 20260303

Add multi-page PDF support, expand USA tier to 219 species, add all 4 vignettes

Update species verification note for bollworm replacement

Add Spodoptera frugiperda examples for paper supplementary

Update docs, gitignore, examples, and vector DB

Simplify RAG prompt, add common name display, add example runner

start feb l2