chore: consolidate Docs/ into docs/ (single documentation directory)

Move UML/ directory and Architecture.md from Docs/ to docs/.
Rename Architecture.md to UML_ARCHITECTURE.md to avoid collision
with existing docs/ARCHITECTURE.md (docs organization file).

Update all references in README.md, CONTRIBUTING.md, CLAUDE.md,
and the architecture file itself.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/UML/html/index.html/assets/css/jquery.bonsai.css

@@ -0,0 +1,36 @@
+.bonsai,
+.bonsai li {
+  margin: 0;
+  padding: 0;
+  list-style: none;
+  overflow: hidden;
+}
+
+.bonsai li {
+  position: relative;
+  padding-left: 1.3em; /* padding for the thumb */
+}
+
+li .thumb {
+  margin: -1px 0 0 -1em; /* negative margin into the padding of the li */
+  position: absolute;
+  cursor: pointer;
+}
+
+li.has-children > .thumb:after {
+  content: '▸';
+}
+
+li.has-children.expanded > .thumb:after {
+  content: '▾';
+}
+
+li.collapsed > ol.bonsai {
+  height: 0;
+  overflow: hidden;
+}
+
+.bonsai .all,
+.bonsai .none {
+  cursor: pointer;
+}