feat(app): v2 desktop UI improvements

[arvsrn]

Issue for this PR

N/A

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

• Added v2 settings screens (general/shortcuts/providers/models)
• Improved home/sidebar/session UX
• Added search menu + keyboard shortcuts (including some tab shortcuts)
• New project avatars with loading/unread states
• Migrated to new toast flow and updated callsites
• Updated several v2 UI component styles (select/button/icon/switch/tabs/etc.)
• Switched to Inter Variable (gated behind non-prod builds only)

How did you verify your code works?

• Ran the app locally and verified the updated UI manually
• Ran type checks locally (bun turbo typecheck)
• Built a local prod build and confirmed v2 changes are excluded

Screenshots / recordings

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

Hey! Your PR title Desktop UI v2 improvements doesn't follow conventional commit format.

Please update it to start with one of:

• feat: or feat(scope): new feature
• fix: or fix(scope): bug fix
• docs: or docs(scope): documentation changes
• chore: or chore(scope): maintenance tasks
• refactor: or refactor(scope): code refactoring
• test: or test(scope): adding or updating tests

Where scope is the package name (e.g., app, desktop, opencode).

See CONTRIBUTING.md for details.

[github-actions]

Thanks for updating your PR! It now meets our contributing guidelines. 👍