docs: add LICENSING.md pointing at canonical Lux IP strategy

Single LICENSING.md file referencing the canonical three-tier IP and
licensing strategy at github.com/luxfi/.github/blob/main/profile/README.md.

LICENSE file is unchanged; this only adds a navigational pointer.

LICENSING.md

@@ -0,0 +1,12 @@
+# Licensing
+
+This repository is licensed under the **BSD 3-Clause License** (see
+[LICENSE](LICENSE)). It belongs to the **public** tier of the Lux
+three-tier IP strategy: anyone may use, fork, or redistribute it,
+including for commercial purposes, subject to the BSD-3 terms.
+
+For the canonical Lux IP and licensing strategy, see:
+<https://github.com/luxfi/.github/blob/main/profile/README.md>
+
+For commercial inquiries that go beyond BSD-3 (e.g. private moat
+acceleration kernels), contact `[email protected]`.