Function applyNappletRules

applyNappletRules(config: GuardConfig, napplet: string): GuardConfig
Register the profile's per-class rates for one applet in the kehto firewall.

kehto's rateLimits map is keyed by applet identity, so class rates cannot live in a fresh config. The focus firewall calls this lazily on the first observation of an applet; core may call it earlier, when a window binds, so that a user's per-applet policy and the rates land in one config. Existing policy and matchers are preserved; rates for the applet are overwritten.
Parameters
- config: GuardConfig
  Current guard configuration.
- napplet: string
  Applet identity (dTag) to register rules for.
Returns GuardConfig
A new guard configuration; the input is not modified.
Example
```
const bound = applyNappletRules(createGuardConfig('strict'), 'chat');
bound.firewall.napplets.chat?.rateLimits['relay:publish']?.capacity; // 20
```