feat(docs): add architecture/roadmap (#9624)

* feat(docs): Add architecture overview

* add strucutre for rough roadmap

* add stable reference

* document stable links

* test mermaid again

* fix loading

* fix format to reduce warnings

* use local js

* add architecture ovierview

* add more sub-points

* more structure

* add general backend text

* add sme bqsic docs for frontend

* fix list syntax

* fix typo

docs/requirements.in

@@ -7,3 +7,4 @@ mkdocs-simple-hooks>=0.1,<1.0
 mkdocs-include-markdown-plugin
 neoteroi-mkdocs
 mkdocstrings[python]>=0.25.0,<=0.29.1
+mkdocs-mermaid2-plugin