Bump version to 4.0.1 with Web UI improvements

- Update version to 4.0.1 across constants.py, __init__.py, pyproject.toml, README
- Refactor channel key UI from radio buttons to select dropdown
- Add LED indicator and key capsule CSS styles
- Reorganize encode/decode forms: RSA key section moved up, PIN + Channel in row
- Streamline channel key JavaScript for dropdown-based selection

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "stegasoo"
-version = "4.0.0"
+version = "4.0.1"
 description = "Secure steganography with hybrid photo + passphrase + PIN authentication"
 readme = "README.md"
 license = "MIT"