One brand package

• Context: the product’s name must change in one place.
• Decision: every user-visible name derives from internal/brand; internal names are brand-neutral (X-Loop-*, LOOP_*); the docs write the name through placeholders.
• Consequence: a build with another name writes nothing that names the default one.
• Enforced by: TestBrandLiteralOnlyInBrand, make test-brand, make scan-brand.