[codex] Add webchat teaser positioning behavior

[rockwellll]

What changed

• Adds webchat teaser behavior that positions the teaser separately from the main popover, hides it when the webchat opens, and only shows it again when teaser body content exists.
• Keeps the emoji picker positioned with an absolute floating strategy.
• Adds regression coverage for teaser positioning, teaser open/close visibility, usePopover strategy overrides, and emoji picker positioning.
• Includes updated generated lib and dist outputs.

Why

The teaser and emoji picker need their own positioning behavior so they do not inherit the main webchat strategy in cases where that would place the floating UI incorrectly. The teaser also should not reappear when there is no teaser body to show.

Validation

• npm test

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Note

Medium Risk
Touches webchat popover positioning and open/close UI behavior, which could cause regressions in widget layout/visibility across configurations and devices.

Overview
Adds support for overriding usePopover’s Floating UI strategy per popover (falling back to Configuration.webchat.strategy when omitted).

Updates WebchatController to position the teaser independently from the main popover using strategy: 'absolute', hide the teaser when the chat opens, and only re-show it on close when teaserValue.body is present; keeps EmojiPickerController explicitly positioned with strategy: 'absolute'. Includes new Jest coverage for usePopover strategy selection, teaser positioning/visibility, and emoji picker positioning, and updates generated lib outputs accordingly.

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