feat: add contact payment ui

[ben-kaufman]

Description

This PR:

1. Adds Send → Contact selection so saved contacts can be chosen from the send sheet.
2. Adds contact attribution UI on Activity Detail, including assigning and detaching a contact.
3. Shows contact avatars in the main and full activity lists while keeping the contact-specific activity list on the existing arrow style.
4. Adds Payment Preference settings for Lightning/on-chain methods and public/private contact sharing.
5. Wires public/private Paykit endpoint publishing to the selected payment preferences.

Preview

Send → Contact Full Flow

Proof: saved contact selection opens the normal send flow, keeps Bob's avatar in the top-right on the amount and confirmation screens, and shows Bob as the recipient in confirmation details.

01-send-contact-full-flow.mp4

Activity Rows Contact Avatar

Proof: contact-attributed payments show contact avatars in both the wallet home activity list and the full All Activity list.

02-activity-rows-contact-avatar.mp4

Activity Detail Assign And Detach

Proof: assigning Bob shows the assigned contact next to tags, and Detach returns the activity to the unassigned state.

03-activity-detail-assign-detach-fullscreen.mp4

Payment Preference

Proof: the Payment Preference screen shows Lightning, On-chain, Private payments with contacts, and Public payments with contacts as clean title-only rows, with the switches updating the selected preferences in place.

04-payment-preference-no-subtitles.mp4

QA Notes

Manual Tests

• 1. Wallet → Send → Contact: saved contacts appear and tapping one opens the normal send flow for that contact.
• 2. Activity → Activity Detail → Assign: contact picker opens, selecting a contact shows the assigned contact section, Detach removes it.
• 3. Activity list → contact-attributed payment: main and full activity lists show the contact avatar instead of the arrow icon.
• 4. Contact Detail → Activity: contact-specific activity rows still show the arrow icon and the contact wording.
• 5. Settings → General → Payment Preference: Lightning/on-chain toggles cannot both be disabled; public/private contact toggles sync Paykit sharing state.

Automated Checks

• Local checks passed: ./gradlew compileDevDebugKotlin, ./gradlew testDevDebugUnitTest, ./gradlew detekt, git diff --check.
• E2E build passed: E2E=true E2E_BACKEND=network ./gradlew assembleDevDebug --no-daemon --stacktrace.
• Android emulator proof videos are linked above as GitHub PR attachments for Send → Contact, Activity rows, Activity Detail assign/detach, and Payment Preference.

[chatgpt-codex-connector]

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[ben-kaufman]

Updated to fix point 1 in both PRs