Relicense under PolyForm Noncommercial 1.0.0

Switches the project from Apache-2.0 to PolyForm Noncommercial 1.0.0.
Use, modification, redistribution, forking and contribution are all
permitted; the only thing the new license withholds is commercial sale
of the software or of services built primarily around it.

Updates: LICENSE file, workspace Cargo license metadata, the Python
pyproject classifier and SPDX field, and the Node package.json. The
README now explains the practical scope in plain English.

bindings/python/pyproject.toml

@@ -7,13 +7,13 @@ name = "wickra"
 version = "0.1.0"
 description = "Streaming-first technical indicators: incremental, fast, install-free."
 readme = "../../README.md"
-license = { text = "Apache-2.0" }
+license = { text = "PolyForm-Noncommercial-1.0.0" }
 requires-python = ">=3.9"
 keywords = ["finance", "trading", "indicators", "technical-analysis", "ta-lib"]
 classifiers = [
     "Development Status :: 4 - Beta",
     "Intended Audience :: Financial and Insurance Industry",
-    "License :: OSI Approved :: Apache Software License",
+    "License :: Free for non-commercial use",
     "Programming Language :: Python :: 3",
     "Programming Language :: Python :: 3 :: Only",
     "Programming Language :: Python :: 3.9",