Use same version number for server and webapp, add CI check

- Check webapp and server have same version number
- Use `genversion` on build to create javascript file with version string
from pyproject.toml
- Expose the version number in the js interface
- Correct format of current of alpha version string because javascript complains

Closes #382

check_version_sync.py

@@ -0,0 +1,26 @@
+#! /usr/bin/env python3
+
+"""
+A script to check that th npm version string matches the python
+version string exactly.
+"""
+
+import json
+import tomllib
+import os
+
+with open("pyproject.toml", "rb") as toml_f:
+    pyproject_data = tomllib.load(toml_f)
+
+with open(os.path.join("webapp", "package.json"), "r", encoding="utf-8") as json_f:
+    webapp_data = json.load(json_f)
+
+py_ver = pyproject_data["project"]["version"]
+js_ver = webapp_data["version"]
+
+assert py_ver == js_ver, (
+    "The python and javascript version numbers should match.\n"
+    f"Python version: {py_ver}\n"
+    f"Javascript version: {js_ver}\n"
+    ""
+)