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

src/kaya_rbcs/config.py

@@ -0,0 +1,44 @@
+from dataclasses import dataclass, field
+from datetime import timedelta
+from os import getenv
+
+
+def _parse_max_age(raw: str) -> timedelta:
+    if raw.endswith('s'):
+        return timedelta(seconds=int(raw[:-1]))
+    if raw.endswith('m'):
+        return timedelta(minutes=int(raw[:-1]))
+    if raw.endswith('h'):
+        return timedelta(hours=int(raw[:-1]))
+    if raw.endswith('d'):
+        return timedelta(days=int(raw[:-1]))
+    return timedelta(seconds=int(raw))
+
+
+@dataclass(frozen=True)
+class Config:
+    host: str = '127.0.0.1'
+    port: int = 8080
+    path_prefix: str = '/'
+    memcache_host: str = '127.0.0.1'
+    memcache_port: int = 11211
+    key_prefix: str | None = None
+    digest: str | None = None
+    max_age: timedelta = field(default_factory=lambda: timedelta(days=7))
+
+    @staticmethod
+    def from_env() -> 'Config':
+        def get_int(name: str, default: int) -> int:
+            raw = getenv(name)
+            return int(raw) if raw is not None else default
+
+        return Config(
+            host=getenv('RBCS_HOST', '127.0.0.1'),
+            port=get_int('RBCS_PORT', 8080),
+            path_prefix=getenv('RBCS_PATH_PREFIX', '/'),
+            memcache_host=getenv('RBCS_MEMCACHE_HOST', '127.0.0.1'),
+            memcache_port=get_int('RBCS_MEMCACHE_PORT', 11211),
+            key_prefix=getenv('RBCS_KEY_PREFIX'),
+            digest=getenv('RBCS_DIGEST'),
+            max_age=_parse_max_age(getenv('RBCS_MAX_AGE', '7d')),
+        )