- Introduce `ModelPaletteEntry` and re‑export it for external use. - Extend `CommandPalette` with dynamic sources (models, providers) and methods to refresh suggestions based on `:model` and `:provider` prefixes. - Implement fuzzy matching via `match_score` and subsequence checks for richer suggestion ranking. - Add `provider` command spec and completions. - Update UI to display “Model (Provider)” in the header and use the new active model label helper. - Wire catalog updates throughout `ChatApp` (model palette entries, command palette refresh on state changes, model picker integration).