Refactor packages/opencode/src/session/retry.ts retryable error handling

[faboueln]

Issue for this PR

Closes #30

Type of change

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

What does this PR do?

• This PR updates the retryable() function in packages/opencode/src/session/retry.ts after Qlty flagged it for having too many return statements. I broke the function into smaller helper functions so each part handles a specific type of error. This keeps the same behavior, but makes the code easier to follow and removes the Qlty warning about having too many returns.

Please provide a description of the issue, the changes you made to fix it, and why they work. It is expected that you understand why your changes work and if you do not understand why at least say as much so a maintainer knows how much to value the PR.

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How did you verify your code works?

• I tested the changes by running bun test test/session/retry.test.ts, and all 52 tests passed with no failures. I also checked the coverage using bun test test/session/retry.test.ts --coverage --coverage-dir=./coverage, and retry.ts had 100% function coverage and 97.65% line coverage. After that, I ran Qlty again to make sure the issue was actually fixed, and the original “Function with many returns” warning for retryable() was no longer showing.

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Checklist

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

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