feat: add tool approval and timeout settings

- Introduced ToolApprovalConfig and related types for managing tool execution approvals.
- Implemented WebFetch and ZxScript tools for fetching web content and executing scripts, respectively.
- Added token estimation utilities for context window management.
- Enhanced ModelInfo interface with context window size and max output tokens.
- Created API Retry Utility for handling transient failures with exponential backoff.
- Updated AIAgent preferences section to include Tool Approval & Timeout Settings dialog.
- Developed ToolApprovalSettingsDialog for configuring tool-specific approval rules and retry settings.
- Modified vitest configuration to support aliasing for easier imports and stubbing.

src/services/externalAPI/interface.ts

@@ -147,6 +147,10 @@ export interface ModelInfo {
   features?: ModelFeature[];
   /** Model-specific parameters (e.g., ComfyUI workflow path) */
   parameters?: Record<string, unknown>;
+  /** Input context window size in tokens (e.g. 128000 for GPT-4o, 200000 for Claude) */
+  contextWindowSize?: number;
+  /** Max output tokens (e.g. 4096, 16384) */
+  maxOutputTokens?: number;
   /** Additional metadata */
   metadata?: Record<string, unknown>;
 }