Add Fallback Skills

[Inhishonor]

Dicio supports fallback skills when the app is unable to understand the content. There should be a few fallback skills. Already requested ones are:

• LLM support #132
• Add "nevermind" fallback command #334
• Implement "did you mean" functionality #365

But the following could be implemented as well:

• Re-purposing the search skill
• Or using in-app search like Adds in app search #323

Another potential addition could be that this behavior could be controlled by a setting or user interaction, to pick a default fallback skill, that way random gibberish isn't redirected to an LLM.