#7496: feat: add copy-templates script and workspace template resolution

This PR adds the `scripts/copy-templates.ts` utility, includes it in the build, and adds tests and workspace template resolution behavior. Files of interest: - `scripts/copy-templates.ts` (+ test) - `src/agents/workspace.ts` (+ test) Tests pass locally (`src/scripts/copy-templates.test.ts`). Notes: - This is primarily a tooling addition (templates copy + tests). Recommend @joshp123 for review (workspace / Nix familiarity). - Backup branch with original commits: `backup/feat/pwsh-completion-install-uninstall-before-reset`. /cc @joshp123