feat: begin integrating WuttaWeb as upstream dependency

the bare minimum, just to get the relationship established.  mostly
it's calling upstream subscriber / event hooks where applicable.

this also overhauls the docs config to use furo theme etc.

pyproject.toml

@@ -59,12 +59,13 @@ dependencies = [
         "transaction",
         "waitress",
         "WebHelpers2",
+        "WuttaWeb",
         "zope.sqlalchemy>=1.5",
 ]
 
 
 [project.optional-dependencies]
-docs = ["Sphinx", "sphinx-rtd-theme"]
+docs = ["Sphinx", "furo"]
 tests = ["coverage", "mock", "pytest", "pytest-cov"]