Add ESLint v9.35+ with typescript-eslint recommended config and
error-handling rules: preserve-caught-error (enforces { cause } when
re-throwing), no-unused-vars with caughtErrors:all, and
eslint-plugin-no-catch-all (warns on catch blocks that don't rethrow).
Fix existing violations: add error cause to container-runtime rethrow,
prefix unused vars with underscore, remove unused imports.
https://claude.ai/code/session_01JPjzhBp9PR5LtfLWVDrYrH
