Add insect domain + fungi summary blurb fallback + seed_fungi
Insect domain (migration 016): insects table with order/family taxonomy,
beneficial/pest role, beneficial_roles, pest_severity, host_plant_slugs,
preys_on, life cycle, active months, attracted_by (cross-domain plant links).
Insect+CreateInsect models, db/insects.rs CRUD (role/order filters),
api/insects.rs, /api/v1/insects routes + summary. Wired into stats/export/llms.
Fungus summary now falls back to culinary_uses/habitat for the blurb.
seed_fungi.py committed (15 curated mushrooms).
florian.berthold
2cfa57a188