feat: add Paykit subscriptions

[ben-kaufman]

Description

Adds the payer side of Paykit subscriptions, stacked on #683.

• Receives private subscription proposals and lets the payer review and confirm them.
• Requires an immediately due first period to be paid before showing the subscribed success state; failed or uncertain payments remain due and can be retried.
• Turns each unpaid billing period into the existing incoming payment-request flow, including automatic presentation, the bell queue, and the Payments tab.
• Schedules local due-payment notifications and opens the corresponding request when the notification is selected.
• Adds the Figma-aligned Subscriptions and Payments tabs, subscription detail/status views, cancellation, empty states, and fixed/open-ended summaries.
• Shows a normalized Monthly Cost across all active subscriptions, independent of whether the current periods are already paid.
• Associates payment proofs with their exact billing period so recurring periods remain independent while retaining private-only resolution and fresh Private Payment List requirements.
• Keeps subscribe-and-pay inside one continuously presented sheet, including initial-payment failure and retry, without the modal dismissal/reappearance gap.
• Retains the settled payment rail in completed request and subscription history so Lightning feedback is purple and on-chain feedback is orange, including success confetti.

This PR intentionally covers payer-side receipt only. Subscription creation, Discover, automatic payment without confirmation, and renewal are not included because they are outside this MVP or are not currently exposed by Paykit.

Dependencies:

• Paykit 0.1.0-rc46
• Payment proof delivery #683

Linked Issues/Tasks

• Figma subscriptions overview
• Android companion PR #1186

Screenshot / Video

Final iOS and cross-platform proof recordings were completed locally; they are not attached to the PR.

QA Notes

Manual Tests

• Receive an immediate-start private subscription proposal and verify review → payment → success stays in one continuously presented sheet.
• Exercise failed and uncertain initial payments and verify retry stays in the same sheet while the first period remains due.
• Complete Lightning and on-chain subscription payments and verify purple/orange success confetti and matching completed-payment icons.
• Receive a future-start proposal, trigger its due notification, and open the exact billing-period payment.
• Dismiss and reopen a due request from the bell queue and Payments tab, then pay it with fresh private payment details.
• Review active, expired, fixed-term, and open-ended subscription details and cancel an active subscription.

Automated Checks

• 99 focused PaykitPaymentRequestServiceTests and PaykitPaymentProofServiceTests
• E2E regtest Debug build for an arm64 iOS simulator
• Exact build installed and cold-launched on an iOS simulator
• SwiftFormat validation for all 13 changed Swift files
• Localization validation
• git diff --check

[ben-kaufman]

Restacked on the updated payment-proof branch at c3f2d8c. The subscription layer is unchanged; all commits remain signed, and the complete payment-proof suite (including recurring periods and uncertain on-chain recovery) passes 22/22.

[ben-kaufman]

Restacked again on the final signed payment-proof hardening head 281b8654; current signed subscriptions head is cf4cea28. Focused PaykitPaymentProofServiceTests: 21/21 passing.

[ben-kaufman]

The subscriptions branch is now correctly restacked on the current signed #683 head (6bcff553); the subscription-only head is c274b0a4, and every commit is verified. After restacking, PaykitPaymentProofServiceTests, PaykitPaymentRequestServiceTests, and PaymentNavigationHelperTests pass 112/112. The earlier details-flow and payment-sheet sequencing fixes remain present. @ovitrif @jvsena42 please re-review the current head; fresh CI is still running.

[ben-kaufman]

Restacked onto #683 signed head 489b1e61; the new subscriptions head is e6416820. The one conflict was in the shared secondary button and was resolved by keeping the subscriptions/Figma-correct shared height plus #683’s shouldExpand behavior. All five subscriptions commits were re-signed.

Post-restack simulator verification passes 134/134 across HwFundingSignerTests, PaykitPaymentProofServiceTests, PaykitPaymentRequestServiceTests, and PaymentNavigationHelperTests.

[ovitrif]

utACK

The base branch was changed.

[ben-kaufman]

Follow-up pushed in db1aeae: definitive hardware broadcast failures now clear a started proof with failOnchainPayment before cancelling any unstarted preparation. This prevents a failed hardware broadcast from leaving an orphaned started proof, while uncertain broadcasts remain persisted for reconciliation. Focused PaykitPaymentProofServiceTests pass 23/23, and SwiftFormat plus diff validation are clean.

[ovitrif]

utACK

[ben-kaufman]

Updated per the Figma clarification: the overview now shows a normalized Monthly Cost across all active subscriptions, independent of whether their current periods are paid. Daily, weekly, monthly, and yearly recurrences are annualized to a monthly value; each subscription is rounded to the nearest satoshi before safe aggregation. The obsolete calendar-month refresh was removed, and regression coverage includes recurrence normalization, paid active subscriptions, inactive exclusions, and low-value rounding.

[ovitrif]

PaykitPaymentRequestManager.acceptedAt(for:) is unused after Monthly Cost stopped reading calendar-month due counts.

The hardware before-broadcast path now marks the on-chain proof started.