chore: establish M0 project foundations

Document accepted MVP decisions, add AGPL-3.0-only licensing, scaffold repository boundaries, and configure verified PSR-12 and foundation checks.

Refs #1, #2, #3, #4, #5

public/README.md

@@ -0,0 +1,6 @@
+# Future HTTP document root
+
+M1 issue #7 adds the PHP front controller; issue #9 adds generated assets in
+`build/` (ignored by Git). Configure the web server to expose only this directory,
+never the repository, credentials or managed library directly. Model downloads
+must go through validated application file IDs. This is not yet a runnable site.