Custom tool loading crashes on transient dependency install failures

[sauerdaniel]

Problem

1. Config.waitForDependencies() runs bun install once and silently swallows failures. On Windows, transient file locks can cause this to fail.
2. ToolRegistry.getCustom() directly imports each tool module without isolation — one broken custom tool crashes loading for all custom tools.

Expected behavior

• Transient dependency install failures should be retried before giving up
• A broken custom tool module should not prevent other tools from loading

Environment

• Primarily affects Windows (file lock contention during bun install)
• Also affects any environment where a custom tool module has a syntax/runtime error

[github-actions]

This issue might be a duplicate of or related to existing issues. Please check:

• Custom Tools Failing with TypeError #13365: Custom Tools Failing with TypeError (also involves Windows and custom tool failures)
• Bug: Zod TypeError when loading custom tools from .opencode directory #12336: Bug: Zod TypeError when loading custom tools from .opencode directory (also involves custom tool loading failures)

Please verify if these are the same root cause or different issues before proceeding.