fix(license): add missing SPDX headers to environment-catalogs.ts (dev full-test red)

[LeXwDeX]

What

packages/opencode/src/dag/environment-catalogs.ts (introduced in #361 / PR #361's catalog-loader extraction) shipped without the SPDX copyright/license header. The core license-scope manifest test catches it — dev's push-triggered full test has been red on every merge since 698713c (4 consecutive failures, 2026-08-19 04:51→06:00).

The PR→dev Typecheck gate cannot see this class of breakage (it is a unit-test assertion); the push-on-dev full run caught it within minutes of merge — the layered gating working as designed.

Acceptance

• SPDX headers added
• license-scope test green locally
• dev full test green on the merge push

[LeXwDeX]

Delivered via PR #369 (merged to dev); specgit finish exit 0. dev full-test should go green on this push.