Merge pull request #536 from josepe98/fix/handle-missing-api-data

fix: log API failures and handle missing data in Ben Graham agent

Add nassim taleb agent

Add new models

Merge pull request #549 from tsensei/fix/optional-author-company-news

fix: make CompanyNews.author optional to handle missing API data

Merge pull request #530 from mango766/fix/bare-except-api-parsing

Merge pull request #531 from mango766/fix/get-model-missing-providers

fix: add missing provider support and remove duplicate import in models.py

fix: replace bare except clauses with Exception in api.py

Merge pull request #499 from stablegenius49/pr-factory/issue-418-short-margin-available-cash

Merge pull request #502 from Bortlesboat/fix/sortino-downside-deviation

fix: use target downside deviation in Sortino ratio

Fix short position cash check to use available cash (margin-aware)

Add frontier models