#11185: fix #11150 - [Bug]: Exec tool schema host default ignores tools.exec.host config

## Description Fixes issue #11150 ## Changes Modified createExecTool to dynamically set the default value for the host parameter in the tool schema using the provided configuration. <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR updates `createExecTool` to set the `host` parameter’s schema default dynamically from `defaults?.host` (falling back to `"sandbox"`), so generated tool schemas reflect `tools.exec.host` configuration instead of always defaulting to sandbox. The change is localized to `src/agents/bash-tools.exec.ts` and affects the tool schema metadata used for parameter validation/introspection. <h3>Confidence Score: 3/5</h3> - This PR is close to mergeable, but the schema-spread approach risks breaking TypeBox schema integrity in tooling/validation paths. - The functional intent is clear and the behavioral change is small, but mutating a TypeBox schema via object spread can drop internal metadata and cause runtime issues in parameter validation/introspection. Fixing the schema construction to use TypeBox APIs should make this safe. - src/agents/bash-tools.exec.ts <!-- greptile_other_comments_section --> <!-- /greptile_comment -->