fix: use core LNURL-pay validation

[ovitrif]

Description

This PR:

1. Updates the app from iOS release v2.3.0 to bitkit-core 0.1.74.
2. Routes LNURL-pay invoice fetching through generated core bindings with full LnurlPayData.
3. Removes local LNURL-pay invoice callback fetching while leaving withdraw/channel behavior unchanged.
4. Handles core invoice validation errors with a neutral payment-canceled message.

Patch commit: c522b5cc3cc223bc87e0158cfe749129eac83844
Core release: https://github.com/synonymdev/bitkit-core/releases/tag/v0.1.74

Linked Issues/Tasks

Refs:

• fix: validate LNURL-pay amount bitkit-core#115
• fix: use core LNURL-pay validation bitkit-android#1048

Screenshot / Video

N/A

QA Notes

Manual Tests

• 1. Send -> scan LNURL-pay request -> complete payment: invoice fetch and send behavior match the requested payment.
• 2. regression: Send -> scan LNURL-withdraw or LNURL-channel request: existing withdraw/channel behavior still works.

Automated Checks

• Local verification: swiftformat --lint for touched Swift files, xcodebuild build.
• Runtime proof: Android and iOS before/after LNURL-pay validation recordings completed locally.

[ovitrif]

added a few nits that must be addressed. PR changes should be squashed into a single commit with same message as PR name

[ovitrif]

added a few nits that must be addressed. PR changes should be squashed into a single commit with same message as PR name

Addressed the review thread and squashed the branch into a single commit named fix: use core LNURL-pay validation.

Resolved in c522b5c

[piotr-iohk]

LGTM. Staging regtest: normal LN + QuickPay on/off OK. CI @lnurl_1 passed — sufficient regression for the LNURL-pay validation hotfix. Good to merge once all e2e pass.

[jvsena42]

utAck, Changes looks solid and self contained