chore(license): align Cargo.toml license field to LICENSE (MIT OR MPL-2.0 → MPL-2.0)

Closes #48.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

Cargo.toml

@@ -12,7 +12,7 @@ version = "1.0.0"
 edition = "2021"
 rust-version = "1.70"
 authors = ["Vext Contributors"]
-license = "MIT OR MPL-2.0"
+license = "MPL-2.0"
 repository = "https://github.com/Hyperpolymath/vext"
 
 [workspace.dependencies]