fix(chat): Add programmer card on top of the page.

[Randall-Jiang]

Problem

We want to show the programmer card on top of the page. And change the welcome message

Solution

---

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[github-actions]

• This pull request modifies code in src/* but no tests were added/updated.
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• This pull request implements a feat or fix, so it must include a changelog entry (unless the fix is for an unreleased feature). Review the changelog guidelines.
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[zixlin7]

you probably can update this one instead: https://github.com/aws/aws-toolkit-vscode/blob/master/packages/core/src/amazonq/webview/ui/tabs/constants.ts#L9

[Randall-Jiang]

The reason I add the seperate welcomeMessage here is I don't want to mess up the current user experience since I only got the UI for agentic chat. I will update constants.ts if we finalize that we are using the same welcome message globally