feat(engine): generate_brands pipeline — 10K minor brands from templates (#829)

New generate_brands binary reads 126 brand archetype templates
(wiki/economics/archetypes/brand_templates.toml), assigns halo+volume pairs
to all 48 hand-authored corps, outputs wiki/economics/corporations/generated_brands.toml.

Result: 10,000 brand_product rows, 26,750 brand_inputs, all 48 corps covered.
Brand structural validation V-B01..V-B06 passes. Generated file is gitignored
(regenerated on each `make economy-db` run).

make economy-db now runs generate-brands before import_economics.py.
import_economics.py merges generated_brands.toml alongside hand-authored brands.toml.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Makefile

@@ -328,6 +328,8 @@ db-install:
 	@tooling/db-install
 
 economy-db:  ## Import economics data (commodities, chains, gate links) into systems.db
+	@echo "  Generating minor brands (D-189 #829)..."
+	@tooling/generate-brands
 	@python3 tooling/economy-db/import_economics.py
 
 atlas-generate:  ## Generate atlas markers (cities, roads, rail) for all inhabited bodies (#832)