refactor: replace Redis references with Valkey in tests and cache modules

Updated test cases in `ValkeyEventStoreTest` and cache implementation in `ValkeyDistributedCache` to fully transition from Redis to Valkey. Adjusted configurations, templates, connection handling, and exception management to reflect Valkey-specific behavior and APIs.

gradle/libs.versions.toml

@@ -59,6 +59,7 @@ flyway = "11.19.1"
 redisson = "4.0.0"
 # Spring Boot 3.5.x manages Lettuce 6.6.x; keep aligned to avoid binary/API mismatches.
 lettuce = "6.6.0.RELEASE"
+springDataValkey = "0.2.0"
 
 # Observability
 micrometer = "1.16.1"
@@ -229,6 +230,7 @@ flyway-postgresql = { module = "org.flywaydb:flyway-database-postgresql", versio
 
 redisson = { module = "org.redisson:redisson", version.ref = "redisson" }
 lettuce-core = { module = "io.lettuce:lettuce-core", version.ref = "lettuce" }
+spring-data-valkey = { module = "io.valkey.springframework.data:spring-data-valkey", version.ref = "springDataValkey" }
 
 micrometer-prometheus = { module = "io.micrometer:micrometer-registry-prometheus", version.ref = "micrometer" }
 micrometer-tracing-bridge-brave = { module = "io.micrometer:micrometer-tracing-bridge-brave", version.ref = "micrometerTracing" }
@@ -342,8 +344,7 @@ database-complete = [
   "flyway-postgresql"
 ]
 valkey-cache = [
-  "spring-boot-starter-data-redis",
-  "lettuce-core",
+  "spring-data-valkey",
   "jackson-module-kotlin",
   "jackson-datatype-jsr310"
 ]