[FEATURE]: add rtk to bash arity dictionary

[bcdady]

`rtk` (github.com/rtk-ai/rtk) has an explicit OpenCode integration (`rtk init -g --opencode`) but is absent from the `ARITY` dictionary in `permission/arity.ts`. As a result, "Always allow" prompts for `rtk` commands produce `rtk *` instead of subcommand-scoped patterns like `rtk env *` or `rtk git clone *`, which is too broad to safely approve.

Add `rtk` and its subcommand prefix depths to the built-in dictionary, consistent with how other multi-level CLI tools (`aws`, `docker`, `kubectl`, etc.) are already represented.

[Arcadi4]

Using my plugin could be a quick workaround. It parses commands and automatically appends rtk, which does not require the model to be aware of rtk. In my opinion, this is also a more stable and context-saving approach by not actively prompting the model.

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Edit: apologies, this would not solve the problem. The tool.execute.before hook used by the plugin happens before the permission check.