Implement kaya-rbcs: simplified RBCS clone on the Kaya framework

- KayaApp with GET/PUT recursive routes backed by memcached (aiomcache)
- env-based configuration, metadata-aware value encoding, key prefix/digest
- Granian RSGI launcher (rbcs-server / python -m kaya_rbcs)
- pinned requirements via pip-compile, alpine:3.24 Dockerfile with healthcheck
- offline tests using an in-process fake memcached
- Gitea Actions workflow to build and push the multi-arch Docker image

requirements.txt

@@ -0,0 +1,31 @@
+#
+# This file is autogenerated by pip-compile with Python 3.14
+# by the following command:
+#
+#    pip-compile --extra-index-url=https://pypi.org/simple --index-url=https://gitea.woggioni.net/api/packages/woggioni/pypi/simple --output-file=requirements.txt requirements.in
+#
+--index-url https://gitea.woggioni.net/api/packages/woggioni/pypi/simple
+--extra-index-url https://pypi.org/simple
+
+aiomcache==0.8.2
+    # via -r requirements.in
+click==8.4.2
+    # via granian
+granian==2.7.9
+    # via
+    #   -r requirements.in
+    #   kaya-rsgi
+kaya-core==0.0.1
+    # via
+    #   -r requirements.in
+    #   kaya-rsgi
+kaya-rsgi==0.0.1
+    # via -r requirements.in
+pwo==0.1.2
+    # via
+    #   kaya-core
+    #   kaya-rsgi
+typing-extensions==4.16.0
+    # via
+    #   kaya-core
+    #   pwo