[WEB-4687] WIP/PoC support for Stripe hosted checkout

[james-od]

Checklist

• If applicable, unit tests
• If applicable, create follow-up issues for purchases-android and hybrids

Motivation

Description

[RevenueCat-Danger-Bot]

❌ CI Job Failed — lint

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Failed Tests

• Formatting Test//Users/distiller/purchases-ios/RevenueCatUI/Templates/V2/Components/Packages/PurchaseButton/PurchaseButtonComponentView.swift
• Formatting Test//Users/distiller/purchases-ios/Sources/Networking/WebBillingAPI.swift
• Formatting Test//Users/distiller/purchases-ios/Sources/Purchasing/Purchases/Purchases.swift

[RevenueCat-Danger-Bot]

❌ Failures

RevenueCat.xcodeproj is out of sync.

The following Swift files were added but are missing from RevenueCat.xcodeproj:
• RevenueCatUI/Views/WebCheckoutView.swift

To fix: open RevenueCat.xcodeproj in Xcode, add/remove the files above in the appropriate target. Check where similar files in the same directory are assigned if you're unsure which target to use.

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This PR changes 807 lines of production Swift code, over the 300-line limit. Split it into smaller PRs, or add the skip-pr-lines-changed-check label to bypass.

[RevenueCat-Danger-Bot]

	2 Errors
🚫	Label the PR using one of the change type labels. If you are not sure which label to use, choose pr:other.
🚫	Purchases iOS checks failed — see the comment above for details.

Label	Description
pr:feat	A new feature. Use along with pr:breaking to force a major release.
pr:fix	A bug fix. Use along with pr:force_minor to force a minor release.
pr:other	Other changes. Catch-all for anything that doesn't fit the above categories. Releases that only contain this label will not be released. Use along with pr:force_patch, or pr:force_minor to force a patch or minor release.
pr:RevenueCatUI	Use along any other tag to mark a PR that only contains RevenueCatUI changes
pr:next_release	Preparing a new release
pr:dependencies	Updating a dependency
pr:phc_dependencies	Updating purchases-hybrid-common dependency
pr:changelog_ignore	The PR will not be included in the changelog. This label doesn't determine the type of bump of the version and must be combined with pr:feat, pr:fix or pr:other.

Generated by 🚫 Danger

[emerge-tools]

4 builds increased size

Name	Version	Download	Change	Install	Change	Approval
RevenueCat com.revenuecat.PaywallsTester	1.0 (1)	20.3 MB	⬆️ 97.8 kB (0.48%)	74.1 MB	⬆️ 424.7 kB (0.58%)	N/A
BinarySizeTest com.revenuecat.binary-size-test.local-source	1.0 (1)	4.9 MB	⬆️ 37.1 kB (0.76%)	14.6 MB	⬆️ 111.2 kB (0.78%)	⏳ Needs approval
BinarySizeTest com.revenuecat.binary-size-test.cocoapods	1.0 (1)	7.3 MB	⬆️ 52.5 kB (0.72%)	31.8 MB	⬆️ 253.1 kB (0.8%)	⏳ Needs approval
BinarySizeTest com.revenuecat.binary-size-test.spm	1.0 (1)	4.9 MB	⬆️ 31.6 kB (0.64%)	12.6 MB	⬆️ 90.5 kB (0.72%)	⏳ Needs approval

RevenueCat 1.0 (1)
com.revenuecat.PaywallsTester

⚖️ Compare build
⏱️ Analyze build performance

Total install size change: ⬆️ 424.7 kB (0.58%)
Total download size change: ⬆️ 97.8 kB (0.48%)

Largest size changes

Item	Install Size Change
DYLD.String Table	⬆️ 164.3 kB
📝 RevenueCatUI.WebCheckoutViewModel.Objc Metadata	⬆️ 11.7 kB
Code Signature	⬆️ 11.4 kB
DYLD.Exports	⬆️ 6.1 kB
RevenueCat.WebBillingAPI.WebBillingAPI	⬆️ 1.4 kB

View Treemap

BinarySizeTest 1.0 (1)
com.revenuecat.binary-size-test.local-source

⚖️ Compare build
📦 Install build
⏱️ Analyze build performance

Total install size change: ⬆️ 111.2 kB (0.78%)
Total download size change: ⬆️ 37.1 kB (0.76%)

Largest size changes

Item	Install Size Change
DYLD.String Table	⬆️ 8.2 kB
DYLD.String Table	⬆️ 6.3 kB
📝 RevenueCatUI.HostedCheckoutSheetPresentationModifier.body(content...	⬆️ 2.9 kB
📝 RevenueCatUI.WebCheckoutViewModel.keyWindow	⬆️ 2.3 kB
RevenueCat.Result.parseResponse(using)	⬆️ 2.1 kB

View Treemap

BinarySizeTest 1.0 (1)
com.revenuecat.binary-size-test.cocoapods

⚖️ Compare build
📦 Install build
⏱️ Analyze build performance

Total install size change: ⬆️ 253.1 kB (0.8%)
Total download size change: ⬆️ 52.5 kB (0.72%)

Largest size changes

Item	Install Size Change
DYLD.String Table	⬆️ 65.1 kB
DYLD.String Table	⬆️ 44.7 kB
Code Signature	⬆️ 3.2 kB
Code Signature	⬆️ 2.9 kB
📝 RevenueCatUI.HostedCheckoutSheetPresentationModifier.body(content...	⬆️ 2.9 kB

View Treemap

BinarySizeTest 1.0 (1)
com.revenuecat.binary-size-test.spm

⚖️ Compare build
📦 Install build
⏱️ Analyze build performance

Total install size change: ⬆️ 90.5 kB (0.72%)
Total download size change: ⬆️ 31.6 kB (0.64%)

Largest size changes

Item	Install Size Change
📝 RevenueCatUI.HostedCheckoutSheetPresentationModifier.body(content...	⬆️ 2.9 kB
Code Signature	⬆️ 2.6 kB
📝 RevenueCatUI.WebCheckoutViewModel.keyWindow	⬆️ 2.3 kB
RevenueCat.Result.parseResponse(using)	⬆️ 2.1 kB
RevenueCatUI.PurchaseButtonComponentView.body	⬆️ 1.9 kB

View Treemap

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Comment trigger: Size diff threshold of 100.00kB exceeded

[RevenueCat-Danger-Bot]

❌ CI Job Failed — run-test-ios-26

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