- Add rcd and bp parameters to silv_predict_biomass(); rcd defaults to
  diameter when not provided, bp defaults to NA_real_
- Replace model-specific dispatch (ruiz-peinado only) with universal
  calc_biomass() inner function using eval_env = list(d,h,rcd,bp);
  now all 7 allometric models work out of the box
- Add return_rmse / return_r2 handling inside calc_biomass()
- Fix eq_biomass_cudjoe_2024() returning equation = 'cudjoe-2017' instead
  of 'cudjoe-2024'

Documentation (Roxygen2):
- silv_predict_biomass(): add @param rcd/@param bp; @details lists all 7
  models with input-variable requirements (rcd/bp for menendez-2022)
- eq_biomass_ruiz_peinado_2011(): add explicit softwood species list (10)
  and component hierarchy (AGB/BGB -> structural groups -> components)
- eq_biomass_ruiz_peinado_2012(): add explicit hardwood species list (13)
  and component hierarchy; fix missing comma in @Seealso
- eq_biomass_dieguez_aranda_2009(): rewrite @details with consistent
  format; fix typo 'Pinaster radiata' -> 'Pinus radiata'
- eq_biomass_montero_2005(): replace 'There are 35 species' with explicit
  bulleted species list; add component hierarchy; fix @Seealso comma
- eq_biomass_manrique_2017(): rewrite @details in structured format; fix
  'thin branches' -> 'small branches' to match biomass_models column
- eq_biomass_menendez_2022(): correct species count 15 -> 18 + 3
  functional groups; add non-standard input note (rcd/bp)
- eq_biomass_cudjoe_2024(): rewrite @details in structured format; fix
  'brances' typo in component name

README.md:
- Add 'Suggested companion reading' section with poster DOI
  https://doi.org/10.13140/RG.2.2.28098.75205

inst/references.bib:
- Resolve unresolved merge conflict: keep menendez-2022 and cudjoe-2024
  entries (HEAD), discard palahi-2003 (other branch)
- Add poster BibTeX entry (vazquez-veloso_poster_2025)