[FEATURE] Allow disabling development mode for the logger

### Is your feature request related to a problem or existing issue? Please describe.

Our logging infrastructure is optimized for handling structured JSON log lines, where the entire line is a valid JSON object.

This project uses Zap for logging, which is intended to be used for structured logging. But `Development` mode is enabled, which moves the timestamp, log level, and message out of the JSON:
https://github.com/kubernetes-sigs/node-readiness-controller/blob/4185cf0747286839834b0a7228ceece7b91e69de/cmd/main.go#L114

For example, this is the current output I get:
```
2026-09-15T18:01:30-07:00 INFO Starting EventSource {"controller": "nodereadiness-controller", "controllerGroup": "readiness.node.x-k8s.io", "controllerKind": "NodeReadinessRule", "source": "kind source: *v1alpha1.NodeReadinessRule"}
```

If I flip that flag `Development` flag to `false`, then the entire line is valid JSON:
```
{"level":"info","ts":"2026-09-15T18:01:56-07:00","msg":"Starting EventSource","controller":"node","controllerGroup":"","controllerKind":"Node","source":"kind source: *v1.Node"}
```

### Describe the solution you'd like

We could follow the example of [etcd](https://etcd.io/docs/v3.7/op-guide/configuration/#logging) and add a `--log-format` CLI arg that could be either `json` or `console`, default it to `json`, and allow people to opt in to the development-friendly `console`.

### Describe alternatives you've considered

- We could just hard-code Development = false. I'm not sure how disruptive this would be to your local development though.

### AI Tools Usage

- [x] No AI tools were used
- [ ] AI tools were used (complete below)

### How They Were Used

_No response_

Start in cmd/main.go around the logger setup at line 114 and trace how command-line options are defined and passed into logging. Add a --log-format choice for json or console, keep json as the default, and verify that both formats produce the intended output.

Written by the indexing model from the issue text.