Add setting to disable auto-attaching files to chat input in VS Code

Problem

When using Claude Code in VS Code's native extension, any file that gets created or edited automatically appears as an attached file in the chat input box. The user has to manually click to remove it before sending their next message.

This is particularly disruptive during workflows where Claude is creating or editing files as part of a task (writing specs, generating code, editing configs). Each file operation pollutes the next chat input with an unwanted attachment that has to be manually dismissed.

Expected Behavior

A setting (e.g., claudeCode.autoAttachFiles: false) that prevents recently created/edited files from being auto-attached to the chat input. The user can still manually attach files when needed.

Current Workaround

• Manually click the X on each auto-attached file before sending the next message
• Use Claude Code from the integrated terminal (claude) instead of the extension UI, which doesn't have this behavior

Why This Matters

Power users who run multi-step workflows (spec writing, code generation, file organization) trigger dozens of file creates/edits per session. Each one adds friction by requiring a manual dismiss action before the next message can be sent cleanly.