DEFAULTS_MODE=dev does not set/skip REPLICATION_HOSTNAME during install

## Problem

When running the installer with `DEFAULTS_MODE=dev`, `REPLICATION_HOSTNAME` is not automatically set or skipped. Installers expect dev mode to apply sensible localhost defaults without requiring every replication parameter to be explicitly provided.

## Relevant code

`core/utility/install/installer.ts` — the `DEFAULTS_MODE=dev` branch sets dev config defaults (line ~482) but does not appear to skip or auto-fill the `REPLICATION_HOSTNAME` prompt when `DEFAULTS_MODE=dev` is specified as an env/prompt override.

🤖 Filed by Claude on behalf of Kris.