devlore-inventory generator strips the Apache SPDX header on every regeneration #396

The relicense (#389) added Apache-2.0 SPDX headers to pkg/op/inventory/inventory.gen.go and cmd/star/inventory/inventory.gen.go, but cmd/devlore-inventory does not emit a header — and make generate runs it under every build and test (Makefile:477-478). Any make build/make test therefore rewrites both files headerless, and the next commit that stages them silently undoes the relicense on those two files. Observed in practice minutes after #389 merged: a routine local build left both files modified with exactly the header lines deleted.

Same defect class as the defaultGolangciConfig template #389 already fixed — a generator whose output must carry the header, emitting it from the template rather than relying on a one-time sweep. Fix shape: cmd/devlore-inventory writes the SPDX + copyright lines at the top of its output (matching star lint copyright's expectation so license: auto stays consistent). The two committed files need no separate fix — the first regeneration after the generator change produces them correctly.