Note

Low Risk
Low risk: documentation-only updates plus a small bun test ignore configuration change, with no runtime code changes.

Overview
Updates iOS docs to 4.15.0. Adds a new 4.15.0 changelog entry and bumps SdkLatestVersion on the iOS landing and reference index pages.

Documents custom store products support. Expands PurchaseController and advanced purchasing guidance to cover 4.15.0+ custom (non-StoreKit) products, including how to detect missing sk1Product/sk2Product, use productIdentifier, and avoid calling Superwall.shared.purchase(product) for those cases; also updates transaction docs to include custom in ProductStore values.

Test config: adds bunfig.toml to ignore reference/** in tests.

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