chore: add SPDX headers to source files

Author: hyperpolymath

src/abi/Foreign.idr

@@ -1,3 +1,4 @@
+-- SPDX-License-Identifier: PMPL-1.0-or-later
 ||| ANVOMIDAV — FFI Bridge Declarations
 |||
 ||| This module defines the formal bridge to the native C/Zig implementation.

src/abi/Layout.idr

@@ -1,3 +1,4 @@
+-- SPDX-License-Identifier: PMPL-1.0-or-later
 ||| Memory Layout Proofs — ABI Foundation.
 |||
 ||| This module provides the formal proofs required to ensure that 

src/abi/Types.idr

@@ -1,3 +1,4 @@
+-- SPDX-License-Identifier: PMPL-1.0-or-later
 ||| ANVOMIDAV — ABI Type Definitions
 |||
 ||| This module defines the Application Binary Interface for the project.