📝 add schnee package documentation and usage examples

Author: shinaji

README.md

@@ -1,3 +1,87 @@
+## schnee
+
+`schnee` is a Python package and CLI for working with NFC/RFID tags through a PC/SC
+reader, with a current focus on NTAG profile inspection and NDEF URL writes.
+
+## Installation
+
+Install the package from PyPI:
+
+```bash
+pip install schnee
+```
+
+## Requirements
+
+`schnee` talks to tags through PC/SC, so practical use requires:
+
+- a compatible NFC or smart card reader
+- a working PC/SC stack on the host system
+- access to the target tag
+
+If the PC/SC stack or reader is not available, CLI commands that access hardware
+will fail during reader discovery or card communication.
+
+## CLI Usage
+
+After installation, the `schnee` command is available on your `PATH`.
+
+Show the top-level help:
+
+```bash
+schnee --help
+```
+
+List selectable backends and detected PC/SC readers:
+
+```bash
+schnee backends
+```
+
+Read the current NTAG profile as JSON:
+
+```bash
+schnee ntag read --backend pcsc
+```
+
+Use a specific reader by name:
+
+```bash
+schnee ntag read --backend "pcsc:ACS ACR1252 1S CL Reader PICC 0"
+```
+
+Write a URL as a single NDEF URI record:
+
+```bash
+schnee ntag write-url --backend pcsc --url "https://example.com"
+```
+
+For NTAG 424 DNA tags that require application authentication before writing,
+provide the current 16-byte AES key as 32 hex characters:
+
+```bash
+schnee ntag write-url \
+  --backend pcsc \
+  --url "https://example.com" \
+  --ntag424-master-key-hex 00112233445566778899aabbccddeeff
+```
+
+## Python API
+
+The stable Python entry points currently exposed by the package are the service
+classes re-exported from `schnee.services`. For example, you can list the
+selectable backends from Python:
+
+```python
+from schnee.services import ListBackendNamesService
+
+backends = ListBackendNamesService.call(ListBackendNamesService.Request())
+print(backends)
+```
+
+This call uses the same backend discovery as `schnee backends`, so it also
+depends on a working PC/SC environment when the PC/SC backend is enabled.
+
 ## Trademarks and Disclaimer
 
 * **Trademarks**: