Initial commit: CLI extraction from yubisignerHEADmain

Extract core signing logic from Stefan Claas's yubisigner GUI
into standalone CLI tool for automation workflows.

Features:
- YubiKey PIV Ed25519 signing (slot 9c)
- 4 hash algorithms (RIPEMD-256, SHA-256, SM3, Streebog-256)
- Identical signature format to original yubisigner
- Command-line interface for scripting

All cryptographic functions are verbatim copies from yubisigner.go
with original line number references preserved in comments.

1 files changed, 22 insertions, 0 deletions

diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..d5d2872
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,22 @@
+MIT License
+
+Copyright (c) 2024 Stefan Claas (original yubisigner)
+Copyright (c) 2026 Gab Virebent (CLI extraction)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.