[SEGDP-2963] Add support for topic deletion via topicctl CLI

[pazhang-25]

• Repl has been set to read only mode to prevent accidental deletes, configurable through CLI flag.
• Delete operation must be confirmed with a yes/no
• Finishing up the work started in add delete topic command #100 and delete topic #163

Functional test / demo:

---

Confirm that topic is an available command under topicctl delete [command]

~/dev/src/github.com/segmentio/topicctl SEGDP-2963/addTopicDelete ❯ go run cmd/topicctl/main.go delete                                                                   12:43:16 PM
Deletes instances of a particular type.

Usage:
  topicctl delete [command]

Available Commands:
  acls        Delete ACLs. Requires providing flags to target ACLs for deletion.
  topic       Delete a topic

Flags:
  -b, --broker-addr string                Broker address
      --cluster-config string             Cluster config
      --conn-timeout duration             Kafka connection timeout (default 10s)
      --dry-run                           Do a dry-run
      --expand-env                        Expand environment in cluster config
  -h, --help                              help for delete
      --sasl-mechanism string             SASL mechanism if using SASL (choices: AWS-MSK-IAM, PLAIN, SCRAM-SHA-256, or SCRAM-SHA-512)
      --sasl-password string              SASL password if using SASL; will override value set in cluster config
      --sasl-secrets-manager-arn string   Secrets Manager ARN to use for credentials if using SASL; will override value set in cluster config
      --sasl-username string              SASL username if using SASL; will override value set in cluster config
      --tls-ca-cert string                Path to client CA cert PEM file if using TLS
      --tls-cert string                   Path to client cert PEM file if using TLS
      --tls-enabled                       Use TLS for communication with brokers
      --tls-key string                    Path to client private key PEM file if using TLS
      --tls-server-name string            Server name to use for TLS cert verification
      --tls-skip-verify                   Skip hostname verification when using TLS
  -z, --zk-addr string                    ZooKeeper address
      --zk-prefix string                  Prefix for cluster-related nodes in zk

Global Flags:
      --debug        enable debug logging
      --no-spinner   disable all UI spinners

Use "topicctl delete [command] --help" for more information about a command.

---

List all topics running locally:

~/dev/src/github.com/segmentio/topicctl SEGDP-2963/addTopicDelete ❯ go run cmd/topicctl/main.go get topics --cluster-config examples/local-cluster/cluster.yaml          12:46:04 PM
[2025-09-17 12:51:17]  INFO Topics:
-----------------------+------------+-------------+-----------+------------
          NAME         | PARTITIONS | REPLICATION | RETENTION |   RACKS
                       |            |             |   MINS    | (MIN,MAX)
-----------------------+------------+-------------+-----------+------------
  topic-default        | 3          | 2           | 100       | (1,1)
  topic-in-rack3       | 9          | 2           | 100       | (1,1)
  topic-static         | 10         | 2           | 290       | (1,2)
  topic-static-in-rack | 9          | 2           | 100       | (1,1)
-----------------------+------------+-------------+-----------+------------

---

Delete topic-default

~/dev/src/github.com/segmentio/topicctl SEGDP-2963/addTopicDelete ❯ go run cmd/topicctl/main.go delete topic topic-default --cluster-config examples/local-cluster/cluster.yaml
[2025-09-17 12:52:26]  INFO Checking if topic topic-default exists...
[2025-09-17 12:52:26]  INFO Topic topic-default exists in the cluster!
Delete topic "topic-default" (yes/no) yes
[2025-09-17 12:52:29]  INFO Topic topic-default successfully deleted

---

Confirm that topic-default has been deleted

~/dev/src/github.com/segmentio/topicctl SEGDP-2963/addTopicDelete ❯ go run cmd/topicctl/main.go get topics --cluster-config examples/local-cluster/cluster.yaml          12:52:29 PM
[2025-09-17 12:53:11]  INFO Topics:
-----------------------+------------+-------------+-----------+------------
          NAME         | PARTITIONS | REPLICATION | RETENTION |   RACKS
                       |            |             |   MINS    | (MIN,MAX)
-----------------------+------------+-------------+-----------+------------
  topic-in-rack3       | 9          | 2           | 100       | (1,1)
  topic-static         | 10         | 2           | 290       | (1,2)
  topic-static-in-rack | 9          | 2           | 100       | (1,1)
-----------------------+------------+-------------+-----------+------------