Add redis: Boot 4.1 + Spring Data Redis 4.1, the JDK-serialisation default vs Jackson 3 serializers, @RedisHash TTL and keyspace events, @RedisListener, and Redis as the Spring cache

Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01B38FGKKam5SCGgwgduVAh3

redis/docs/output/03-default-template-increment.txt

@@ -0,0 +1,17 @@
+# INCR works with the default template, but the template cannot read the counter it made
+
+
+--- Increment a counter ---
+redisTemplate.opsForValue().increment("hits") = 1
+
+--- What redis-cli sees ---
+$ redis-cli -p 6390 --no-raw KEYS '*'
+1) "\xac\xed\x00\x05t\x00\x04hits"
+$ redis-cli -p 6390 --no-raw EVAL 'return redis.call("GET", redis.call("KEYS", "*")[1])' 0
+"1"
+
+--- Read it back through the same template ---
+redisTemplate.opsForValue().get("hits")
+org.springframework.data.redis.serializer.SerializationException
+  message: Cannot deserialize
+  root:    java.io.EOFException: null