feat(settings): add editor font controls

[rasitakyol]

Description

Add persistent font family and font size controls for Monaco-backed text previews and diffs.

• Adds an independent editor app setting with the current 13px behavior as its default.
• Reuses the terminal font picker and size controls without coupling terminal and editor preferences.
• Applies changes live to existing code editor and diff editor instances, restoring Monaco's captured default font when reset.
• Stores the setting in the existing key-value settings table, so no database migration is required.

This is functionally independent from #2876/#2807, but the branches overlap in four small editor/settings files. I verified the combined result in a temporary integration worktree; whichever PR lands second will need a small rebase. If #2876 lands first, resetting the preference will use its updated Monaco default stack.

Related issues

Fixes #2818.

Testing

• pnpm exec vitest run --project node src/main/core/settings/editor-settings.test.ts src/renderer/tests/editor-config.test.ts src/renderer/features/settings/components/font-settings-cards.test.ts src/renderer/tests/editor-font-live-update.test.ts (12/12)
• pnpm run lint
• pnpm run format:check
• pnpm run typecheck
• pnpm run build:renderer
• Combined feat(ui): modernize monospaced typography #2876 + feat(settings): add editor font controls #2877 integration: 19 focused tests, desktop lint/typecheck/format, and full workspace build passed.
• Broader desktop node suite: one unrelated IssueSelector canvas timeout under concurrent load; the failing test passed when rerun in isolation.
• git diff --check

Screenshot/Recording (if applicable)

Not included. The settings interactions and live Monaco updates are covered by mounted component tests.

Checklist

• I kept this PR small and focused
• I ran a self-review before opening this PR
• I ran the relevant local checks or explained why not
• I updated docs when behavior or setup changed, or docs were not needed
• I added or updated tests when behavior changed, or explained why not
• I only added comments where the logic is not obvious
• I used Conventional Commits for commit messages and, when possible, the PR title

[greptile-apps]

Greptile Summary

This PR adds persistent font controls for Monaco-backed editors. The main changes are:

• Adds independent editor font-family and font-size settings.
• Applies settings live to mounted code and diff editors.
• Extracts shared font controls for terminal and editor settings.
• Adds focused persistence, UI, and live-update tests.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.

Important Files Changed

Filename	Overview
apps/emdash-desktop/src/main/core/settings/schema.ts	Adds validation and registration for the editor typography setting.
apps/emdash-desktop/src/main/core/settings/settings-registry.ts	Adds the default editor font size to the settings registry.
apps/emdash-desktop/src/renderer/features/settings/components/FontSettingsRows.tsx	Extracts reusable font-family and font-size setting controls.
apps/emdash-desktop/src/renderer/features/settings/components/EditorSettingsCard.tsx	Adds independent editor font controls with normalization and size bounds.
apps/emdash-desktop/src/renderer/features/tasks/editor/editor-provider.tsx	Applies editor typography settings to mounted Monaco code editors.
apps/emdash-desktop/src/renderer/lib/monaco/sticky-diff-editor.tsx	Applies editor typography settings to mounted Monaco diff editors.
apps/emdash-desktop/src/renderer/lib/monaco/editor-font-settings.ts	Centralizes Monaco font option construction and default restoration.

_{Reviews (1): Last reviewed commit: "feat(settings): add editor font controls" | Re-trigger Greptile}

[arnestrickmann]

@rasitakyol, thanks for opening the PR -

We’ll review it soon and follow up with feedback here.