ui: Filesystem @mentions for Chat Form (#26715)

* base : @-mention picker foundation - glob search, picker nav, highlight

* feat : @-mention file/folder picker and mention badges in message bubbles

* fix: Imports

* feat : wire the @-mention picker into the chat form

* fix: Bound the glob-search result cache key and prune stale entries

tools/ui/src/lib/constants/settings-keys.ts

@@ -31,8 +31,10 @@ export const SETTINGS_KEYS = {
 	SHOW_MODEL_QUANTIZATION: 'showModelQuantization',
 	SHOW_MODEL_TAGS: 'showModelTags',
 	SHOW_BUILD_VERSION: 'showBuildVersion',
+	SHOW_FULL_PATH_IN_MENTIONS: 'showFullPathInMentions',
 	SHOW_SYSTEM_MESSAGE: 'showSystemMessage',
 	RENDER_THINKING_AS_MARKDOWN: 'renderThinkingAsMarkdown',
+	MENTION_SEARCH_MAX_DEPTH: 'mentionSearchMaxDepth',
 	// Sampling
 	TEMPERATURE: 'temperature',
 	DYNATEMP_RANGE: 'dynatemp_range',