feat(valkey): initial stable release v0.9.0

Valkey (Redis-compatible) client component with launcher lifecycle and health check integration.

What's included:
- Config with Addrs, Password, SelectDB, CacheSizeEachConn (env-driven)
- Provider interface exposing native valkey-go Client() directly (no wrapper)
- Component interface: launcher.Component + health.Checkable + Provider
- New(logger, cfg) constructor for lifecycle registration via lc.Append
- Health check via PING at LevelDegraded priority
- Graceful shutdown calling client.Close() in OnStop

Tested-via: todo-api POC integration
Reviewed-against: docs/adr/

compliance_test.go

@@ -0,0 +1,8 @@
+package valkey_test
+
+import (
+	"code.nochebuena.dev/go/logz"
+	"code.nochebuena.dev/go/valkey"
+)
+
+var _ valkey.Component = valkey.New(logz.New(logz.Options{}), valkey.Config{})