feat(payment): PAYPAL-5723 add bcp button app switch

[bc-yaroslav-zhmutskyi]

What/Why?

Implement AppSwitch functionality for button strategy

Rollout/Rollback

Revert

Testing

Manual

ScreenRecording_cart.mp4

[sentry]

Bug: The renderButton call at line 96 omits isBuyNowFlow, incorrectly enabling appSwitchWhenAvailable in buy-now flows.
_{Severity: CRITICAL | Confidence: 0.95}

🔍 Detailed Analysis

The renderButton method is invoked at line 96 without providing the isBuyNowFlow parameter. This results in isBuyNowFlow being undefined within the method's scope. Consequently, the condition !isBuyNowFlow evaluates to true, causing appSwitchWhenAvailable: true to be incorrectly included in the defaultCallbacks object (lines 115-118) when this.isPaypalCommerceAppSwitchEnabled(methodId) is true, even if the current flow is a buy-now flow. This behavior deviates from the intended logic of enabling app switch only when not in a buy-now flow.

💡 Suggested Fix

Pass the isBuyNowFlow parameter to the renderButton call at line 96. This ensures isBuyNowFlow is correctly evaluated within the method, preventing appSwitchWhenAvailable from being enabled in buy-now flows.

🤖 Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location:
packages/bigcommerce-payments-integration/src/bigcommerce-payments/bigcommerce-payments-button-strategy.ts#L99-L105

Potential issue: The `renderButton` method is invoked at line 96 without providing the
`isBuyNowFlow` parameter. This results in `isBuyNowFlow` being `undefined` within the
method's scope. Consequently, the condition `!isBuyNowFlow` evaluates to `true`, causing
`appSwitchWhenAvailable: true` to be incorrectly included in the `defaultCallbacks`
object (lines 115-118) when `this.isPaypalCommerceAppSwitchEnabled(methodId)` is true,
even if the current flow is a buy-now flow. This behavior deviates from the intended
logic of enabling app switch only when not in a buy-now flow.

_{Did we get this right? 👍 / 👎 to inform future reviews.}