Add GPLv3 license and update file headers

[mattia-moffa]

This uses the headers as currently recommended by the FSF: https://www.gnu.org/licenses/gpl-howto.html#license-notices

[Copilot]

Pull request overview

This PR updates the repository’s licensing to GPLv3 by adding the full GPLv3 license text and aligning existing source file license headers with the FSF-recommended GPLv3 notice format.

Changes:

• Add a top-level LICENSE file containing the GNU GPLv3 text.
• Update license headers across core packages (wolfSSL, wolfx509, wolftls), tests, handles, and examples to reference GPLv3 (or later) and the canonical GNU licenses URL.

Reviewed changes

Copilot reviewed 49 out of 49 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
x509.go	Updates file header to GPLv3 notice format.
wolfx509/x509.go	Updates file header to GPLv3 notice format.
wolfx509/x509_test.go	Updates file header to GPLv3 notice format.
wolfx509/verify.go	Updates file header to GPLv3 notice format.
wolfx509/stdlib_interop_test.go	Updates file header to GPLv3 notice format.
wolfx509/parsecerts_test.go	Updates file header to GPLv3 notice format.
wolfx509/name.go	Updates file header to GPLv3 notice format.
wolfx509/keys.go	Updates file header to GPLv3 notice format.
wolfx509/certificate.go	Updates file header to GPLv3 notice format.
wolfx509/certgen.go	Updates file header to GPLv3 notice format.
wolfx509/certgen_wolfcrypt.go	Updates file header to GPLv3 notice format.
wolfx509/certgen_test.go	Updates file header to GPLv3 notice format.
wolfx509/cert_pool.go	Updates file header to GPLv3 notice format.
wolftls/tls.go	Updates file header to GPLv3 notice format.
wolftls/tls_test.go	Updates file header to GPLv3 notice format.
wolftls/state.go	Updates file header to GPLv3 notice format.
wolftls/listener.go	Updates file header to GPLv3 notice format.
wolftls/init.go	Updates file header to GPLv3 notice format.
wolftls/conn.go	Updates file header to GPLv3 notice format.
wolftls/config.go	Updates file header to GPLv3 notice format.
wolftls/callbacks.go	Updates file header to GPLv3 notice format.
ssl.go	Updates file header to GPLv3 notice format.
sha256/sha256.go	Updates file header to GPLv3 notice format.
sha.go	Updates file header to GPLv3 notice format.
random.go	Updates file header to GPLv3 notice format.
misc.go	Updates file header to GPLv3 notice format.
hmac.go	Updates file header to GPLv3 notice format.
hash.go	Updates file header to GPLv3 notice format.
handles/ecc_handles.go	Updates file header to GPLv3 notice format.
handles/aes_handles.go	Updates file header to GPLv3 notice format.
handles/aes_handles_test.go	Updates file header to GPLv3 notice format.
fips.go	Updates file header to GPLv3 notice format.
examples/x509/extractKey.go	Updates example file header to GPLv3 notice format.
examples/x509/certVerify.go	Updates example file header to GPLv3 notice format.
examples/server/server.go	Updates example file header to GPLv3 notice format.
examples/server/server-psk.go	Updates example file header to GPLv3 notice format.
examples/server/server-dtls.go	Updates example file header to GPLv3 notice format.
examples/hash/fileHash.go	Updates example file header to GPLv3 notice format.
examples/ecc-sign-verify/ecc-sign-verify.go	Updates example file header to GPLv3 notice format.
examples/client/client.go	Updates example file header to GPLv3 notice format.
examples/client/client-psk.go	Updates example file header to GPLv3 notice format.
examples/client/client-dtls.go	Updates example file header to GPLv3 notice format.
examples/aes-encrypt/aes-encrypt.go	Updates example file header to GPLv3 notice format.
ecc.go	Updates file header to GPLv3 notice format.
curve25519.go	Updates file header to GPLv3 notice format.
chacha_poly.go	Updates file header to GPLv3 notice format.
blake2.go	Updates file header to GPLv3 notice format.
aes.go	Updates file header to GPLv3 notice format.
LICENSE	Adds the full GNU GPLv3 license text.

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[lealem47]

Thanks @mattia-moffa