feature: update opencode-work shell function

[sfradkin]

Issue for this PR

Closes #5

Type of change

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

What does this PR do?

update opencode-work shell function with credential check and session resume

If your AWS session already exists it won't re-authenticate
Add an existing opencode session id to resume a session: opencode-work ses-234556677abcde

How did you verify your code works?

Tested the function updates

Screenshots / recordings

N/A

Checklist

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

[github-actions]

Hey! Your PR title feature: update opencode-work shell function 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.