fix: make EditCode independent from chat interface ChatMode (#1086)

[marcoscale98]

Summary

• EditCode now always uses EDIT mode (no backticks) regardless of the chat interface ChatMode setting
• Fixes issue #1086 where backticks were being added to output despite system prompt settings
• Makes EditCode functionality consistent and independent from chat interface

Changes

• Modified EditCodeSubmissionHandler.kt to hardcode ChatMode.EDIT
• Removed dependency on global ChatMode configuration for EditCode
• Added explanatory comments for the design decision

Test plan

• [x] Verified EditCode now uses EDIT mode prompt (no backticks)
• [x] Confirmed EditCode works independently from chat interface ChatMode setting
• [ ] Tested that chat interface ChatMode toggle still works for regular chat"

[carlrobertoh]

I'm not exactly sure how this is going to fix the backtick problem during inline editing. The given modes (ask, edit) are only used for Chat.