Relicense project under the GNU Affero General Public License v3 (AGPLv3)

and add the Enterprise / Commercial licensing option.

Main changes:
- Replace GPLv3 headers with AGPLv3 headers in source files.
- Update LICENSE file to the full AGPLv3 text.
- Add ENTERPRISE.md describing the dual-licensing model:
  * Community Edition: AGPLv3 (strong copyleft, including network use).
  * Enterprise / Commercial Edition: proprietary license for production /
    multi-user / OEM use without the obligation to disclose derivative code.
- Update README with a new "License and Commercial Use" section pointing to
  ENTERPRISE.md and clarifying how companies can obtain a commercial license.

Why this change:
- AGPLv3 ensures that modified versions offered as a service or deployed
  in production environments must provide corresponding source code.
- The Enterprise / Commercial edition provides organizations with an
  alternative proprietary license that allows internal, large-scale, or OEM
  use (bulk provisioning, policy enforcement, inventory / revocation,
  custom attestation, signed builds) without AGPL disclosure obligations.

This commit formally marks the first release that is dual-licensed:
AGPLv3 for the Community Edition and a proprietary commercial license
for Enterprise customers.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>

README.md

@@ -1,4 +1,4 @@
-# Raspberry Pico HSM
+# Pico HSM
 This project aims to transform a Raspberry Pi Pico or ESP32 microcontroller into a Hardware Security Module (HSM). The modified Pico or ESP32 board will be capable of generating and storing private keys, performing AES encryption or decryption, and signing data without exposing the private key. Specifically, the private key remains securely on the board and cannot be retrieved since it is encrypted within the flash memory.
 
 ## Capabilities
@@ -351,6 +351,33 @@ OpenSC relies on PCSC driver, which reads a list (`Info.plist`) that contains a
 - Use the pure-browser online [Pico Commissioner](https://www.picokeys.com/pico-commissioner/ "Pico Commissioner") that commissions the Pico Key on-the-fly without external tools.
 - Build and configure the project with the proper VID/PID with `USB_VID` and `USB_PID` parameters in `CMake` (see [Build section](#build "Build section")). Note that you cannot distribute the patched/compiled binary if you do not own the VID/PID or have an explicit authorization.
 
+## License and Commercial Use
+
+This project is available under two editions:
+
+**Community Edition (FOSS)**
+- Released under the GNU Affero General Public License v3 (AGPLv3).
+- You are free to study, modify, and run the code, including for internal evaluation.
+- If you distribute modified binaries/firmware, OR if you run a modified version of this project as a network-accessible service, you must provide the corresponding source code to the users of that binary or service, as required by AGPLv3.
+- No warranty. No SLA. No guaranteed support.
+
+**Enterprise / Commercial Edition**
+- Proprietary license for organizations that want to:
+  - run this in production with multiple users/devices,
+  - integrate it into their own product/appliance,
+  - enforce corporate policies (PIN policy, admin/user roles, revocation),
+  - and *not* be required to publish derivative source code.
+- Includes access to enterprise-only features (bulk provisioning, multi-user policy controls, device inventory & revocation, custom attestation/identity), official signed builds, and an onboarding call.
+
+Typical licensing models:
+- Internal use (within one legal entity).
+- Redistribution / OEM (shipping this as part of your product).
+
+For commercial licensing and enterprise features, email pol@henarejos.me
+Subject: `ENTERPRISE LICENSE <your company name>`
+
+See `ENTERPRISE.md` for details.
+
 ## Credits
 Pico HSM uses the following libraries or portion of code:
 - mbedTLS for cryptographic operations.