allozaur/feat/chat slash commands (#26716)

* base : slash-command/misc foundation - model icon and focus-selector constants

* feat : slash-command picker and command parsing helpers

* refactor : wire command and @-mention pickers into the chat form

* ui : improve model selector keyboard navigation and load/dismiss

* feat: Unify markdown/raw-text rendering under one setting with migration

* fix: Misc fixes - tool-call subtitle, assistant wrap, progress guards

* feat: Clamp and style numeric settings inputs from registry bounds

tools/ui/src/lib/constants/index.ts

@@ -18,6 +18,7 @@ export * from './binary-detection';
 export * from './built-in-tools';
 export * from './cache';
 export * from './chat-form';
+export * from './chat-commands';
 export * from './cli-flags';
 export * from './code-blocks';
 export * from './icons';