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 +1,18 @@
+# Licensing
+
+This repository is licensed under the **Lux Ecosystem License v1.2**
+(see [LICENSE](LICENSE)). It belongs to the **patent-protected** tier
+of the Lux three-tier IP strategy.
+
+- Free for **Authorized Networks** (Lux Primary NetID=1, EVM 96369;
+  official testnets/devnets; Descending Chains).
+- Free for **Research Use** (academic, education, evaluation).
+- **Commercial use outside Authorized Networks requires a paid
+  commercial license**.
+
+For the canonical Lux IP and licensing strategy and the precise
+definitions of "Authorized Network", "Descending Chain", and "Research
+Use", see:
+<https://github.com/luxfi/.github/blob/main/profile/README.md>
+
+For commercial licensing inquiries, contact `licensing@lux.network`.