fix: remove unused ExplorerMode type from electron/types.ts

The ExplorerMode type was defined in electron/types.ts but never imported
or used. The only active definition is in src/context/ModeContext.tsx.
This change removes the duplicate definition and updates
ConnectionProfile.preferredMode to use an inline union type.

Co-authored-by: Stepan Arsentjev <stepandel@users.noreply.github.com>

Author: github-actions[bot]

electron/types.ts

@@ -50,11 +50,6 @@ export interface HybridEmbeddingConfig {
   defaultAlpha?: number           // Default alpha for queries (0.5 if not set)
 }
 
-/**
- * Explorer mode type - Index Explorer or Assistant Explorer
- */
-export type ExplorerMode = 'index' | 'assistant'
-
 /**
  * Connection profile for Pinecone
  */
@@ -82,7 +77,7 @@ export interface ConnectionProfile {
   textFieldOverrides?: Record<string, string>
 
   // Preferred explorer mode (index or assistant)
-  preferredMode?: ExplorerMode
+  preferredMode?: 'index' | 'assistant'
 }
 
 /**