Allow blacklisting or hiding unwanted models in settings

## Problem

When using JetBrains Central AI provider (or other providers with extensive catalogs), the model selector displays an overwhelming number of models. Central ships past generations alongside multiple dated snapshot releases for each family.

Users who know they never need past generations, dated snapshots, or specific models have no way to hide them.

## Proposed solution

Provide a way in Settings (or directly from the model selector) to blacklist or hide unwanted models:

- Add a setting to configure model blacklist (model ID or glob/regex).
- Optionally allow quickly hiding or dismissing a model directly from the selector interface.

## Alternatives considered

## Additional context


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🤖 Generated by AI agent

No file or test is named. Start by locating the Settings and model-selector entry points, then trace how provider model catalogs are assembled. Done means users can configure model IDs or glob/regex patterns so matching models are hidden, with any direct selector dismissal behavior defined and verified.

Written by the indexing model from the issue text.