#15581: Rename Qianfan label

<!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR updates the onboarding/auth UI label for the `qianfan` provider from "Qianfan" to "Baidu Qianfan", and extends the built-in Qianfan provider model catalog with additional model definitions. The main functional concern is that one of the new Qianfan model entries declares `maxTokens` larger than `contextWindow`, which OpenClaw later clamps during config defaulting; this makes the new definition inconsistent with runtime behavior and should be corrected before merge. <h3>Confidence Score: 4/5</h3> - Mostly safe to merge after fixing one incorrect model limit configuration. - Changes are small and localized, but the new Qianfan `minimax-m2.1` model definition has `maxTokens` exceeding `contextWindow`, which will be silently clamped by config defaults and likely indicates a mistaken value that should be corrected. - src/agents/models-config.providers.ts _{Last reviewed commit: 43d550a} <!-- greptile_other_comments_section --> _{(4/5) You can add custom instructions or style guidelines for the agent [here](https://app.greptile.com/review/github)!} <!-- /greptile_comment -->