fix: repair pipe test and document Bash NVM setup

AGENTS.md

@@ -89,7 +89,9 @@ Do not manually edit generated output or installed dependencies:
 ## Commands
 
 - Node.js must use the `lts/jod` NVM alias, as declared in `.nvmrc`.
-- Before every npm command, run `nvm use lts/jod` in the same shell session. Agent terminal calls do not share shell state, so combine this with the npm command when necessary (for example, `nvm use lts/jod && npm run build`).
+- Documented commands target Bash on Linux, macOS, or Windows WSL. Use Bash explicitly for agent commands; fish's `nvm.fish` is unavailable in Bash.
+- Before every npm command, explicitly load Bash NVM and select Node in the same shell session: `export NVM_DIR="${NVM_DIR:-$HOME/.nvm}"; . "$NVM_DIR/nvm.sh" && nvm use lts/jod && npm run build`. Do not rely on `.bashrc` loading in noninteractive shells or fall back to system Node.
+- If `${NVM_DIR:-$HOME/.nvm}/nvm.sh` is missing, ask the user for permission before installing Bash NVM. Follow `docs/development.md#shell-and-nvm-setup` after approval. Keep existing fish NVM separate.
 - Install exact dependencies: `npm ci`
 - Start the Ionic development server: `npm start`
 - Build the web application: `npm run build`