feat: add font size setting for webview UI

[Ashwinhegde19]

Summary

Adds a font size setting allowing users to customize the webview UI font size (10-24px range, default 13px).

Closes Kilo-Org/kilocode#6308

Changes

File	Change
packages/opencode/src/config/config.ts	Add fontSize schema with min/max validation
packages/kilo-vscode/src/services/cli-backend/types.ts	Add fontSize to Config type
packages/kilo-vscode/webview-ui/src/types/messages.ts	Add fontSize to Config interface
packages/kilo-vscode/webview-ui/src/App.tsx	Apply font size via CSS variables on load/change
packages/kilo-vscode/webview-ui/src/components/settings/DisplayTab.tsx	Add slider UI with validation
packages/kilo-vscode/webview-ui/src/i18n/en.ts	Add English translations

How to Test

1. Open VS Code with Kilo Code extension
2. Open Kilo Code sidebar
3. Go to Settings > Display
4. Adjust the Font Size slider (10-24px)
5. Observe the webview UI text resize immediately
6. Reload VS Code - font size should persist

[markijbema]

Hi! Thank you for taking the time to contribute to this project—we really appreciate it. 🙏

We are currently working on re-platforming the core of our VS Code and JetBrains extensions to be based on our new Kilo CLI, with a complete rebuild based on OpenCode as our new foundation, and the moment has come to promote this repository to become the main repository. To do that, we moved the code from this repository to the kilocode repository.

This unfortunately means we cannot merge this branch here anymore. Please add https://github.com/Kilo-Org/kilocode.git as a remote, and push your branch there and create a new PR in https://github.com/Kilo-Org/kilocode . We unfortunately cannot do this for you as then the PR would not be in your name anymore. If you need any help, feel free to ask on our Discord in #kilo-dev-contributors

Sorry for the inconvenience and thank you for contributing to Kilo!

[Ashwinhegde19]

Requesting credits for this ready-to-merge PR.
Work was done before the repo move.

[markijbema]

Hi @Ashwinhegde19 , without a review, the PR is not ready to merge. I'm sorry for causing the extra work, but you should be able to recreate these PRs on the kilocode repository without extra programming; just add the kilocode repository as a remote, push your branch, and create the PR again. Since that repository has the same git history as this one no rebasing/merging or whatever will even be necessary.

So locally in your branch:

# 1. Add the new repo as a remote (call it whatever you like, e.g. "kilocode")
git remote add kilocode https://github.com/Kilo-Org/kilocode.git

# 2. Fetch from it so you have its refs
git fetch kilocode

# 3. Push your current branch to the new remote
git push kilocode HEAD --no-verify