Instance search should support fuzzy matching

### Current Behavior

Instance names are converted to URL-compliant slugs, which makes it hard for the agent to find instances when users refer to them by their natural language names.

The search should support fuzzy matching so the LLM can locate instances even when the query doesn't exactly match the slug.

Open question: when the name is misspelled or resembles multiple instances, should the LLM return those similar instances as possible results?

### Expected Behavior

_No response_

### Steps To Reproduce

_No response_

### Environment

- FlowFuse version:
- Node.js version:
- npm version:
- Platform/OS:
- Browser:

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate

No files, tests, or entry points are identified. Start by reviewing the current instance-search behavior and slug conversion, then define how fuzzy matches, misspellings, and multiple similar instances should be returned before implementation.

Written by the indexing model from the issue text.