fix(opencode): reroutes install dependencies to .cache instead

[sergentbne]

small patch to make all packages write to .cache instead of dumping plugins to .config.

Issue for this PR

Closes #21966, #3191

Type of change

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

What does this PR do?

Make all dependencies previously written to .config be written now to .cache/opencode/config/deps.

How did you verify your code works?

Ran tests. all passed expect one. the one who didn't pass was not touched during this patch. compared behaviour to current latest on homebrew (stable, not bleeding edge).

Screenshots / recordings

bash-3.2$ ls ~/.config/opencode/
opencode.json
bash-3.2$ opencode
bash-3.2$ ls ~/.config/opencode/
node_modules            opencode.json           package-lock.json       package.json
bash-3.2$ #Current
bash-3.2$ rm -rf ~/.config/opencode/node_modules/
bash-3.2$ rm -rf ~/.config/opencode/package*
bash-3.2$ bun run src/index.ts
bash-3.2$ ls ~/.config/opencode/
opencode.json
bash-3.2$ ls ~/.cache/opencode/config/deps/
node_modules            package-lock.json       package.json
bash-3.2$ #Patch

Checklist

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

[github-actions]

Hey! Your PR title reroutes install dependencies to .cache instead 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.