feat(cli): promote tasks commands from experimental to GA (#20916)

## Overview

This change promotes the tasks CLI commands from `coder exp task` to
`coder task`, marking them as generally available (GA).

## Migration

Users will need to update their scripts from:

```shell
coder exp task create "my task"
```

To:
```shell
coder task create "my task"
```

---

🤖 This change was written by Claude Sonnet 4.5 Thinking using [mux](https://github.com/coder/mux) and reviewed by a human 🏄🏻‍♂️

cli/testdata/coder_task_logs_--help.golden

@@ -0,0 +1,20 @@
+coder v0.0.0-devel
+
+USAGE:
+  coder task logs [flags] <task>
+
+  Show a task's logs
+
+    - Show logs for a given task.:
+  
+       $ coder task logs task1
+
+OPTIONS:
+  -c, --column [id|content|type|time] (default: type,content)
+          Columns to display in table output.
+
+  -o, --output table|json (default: table)
+          Output format.
+
+———
+Run `coder --help` for a list of global options.