Add setting to suppress diff tab opening on Edit/Write

Problem

The VSCode extension unconditionally opens a diff tab (vscode.commands.executeCommand("vscode.diff", ...)) whenever the agent uses Edit or Write tools. There is no user-facing setting to disable this behavior.

For users who auto-accept edits or who prefer to review changes via git diff after the fact, these diff tabs are disruptive — they steal focus and clutter the tab bar.

Requested behavior

Add a setting like claudeCode.showDiffOnEdit (default: true) that, when set to false, applies the edit silently without opening a diff tab.

Current workaround

The only workaround is claudeCode.useTerminal: true, which eliminates the native UI entirely — too heavy-handed for users who just want to suppress diffs.

Environment

• Extension version: 2.1.143
• OS: Windows 11
• VS Code: latest stable