#9045: fix: add clear error message for legacy root-level aliases key

## Problem Fixes #7820 Users with root-level `aliases` in their config (valid in older versions) get a confusing Zod schema error when the gateway fails to start: ``` Unrecognized key(s) in object: 'aliases' ``` ## Solution Add `aliases` to the legacy config rules so users get a clear, actionable error message: ``` Root-level "aliases" is no longer supported. Use `openclaw models aliases add <alias> <model>` to configure model aliases. ``` ## Change Added to `LEGACY_CONFIG_RULES` in `legacy.rules.ts`: ```typescript { path: ["aliases"], message: 'Root-level "aliases" is no longer supported. Use `openclaw models aliases add <alias> <model>` to configure model aliases.', }, ```