desktop: remote OPENCODE_SQLITE env

[Brendonovich]

Removes the OPENCODE_SQLITE env that is in place for gating the sqlite migration loadnig window to only show in beta builds.
We'll want to merge this ONLY after merging sqlite2.

[github-actions]

Hey! Your PR title desktop: remote OPENCODE_SQLITE env 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.