feat: accept allowance offers automatically on the allowee's wallet

[ovitrif]

Closes #1353
Twin: synonymdev/bitkit-ios#841
Stacked on #1340
Refs: #1351

This PR makes the allowee's wallet accept an allowance the allower offers, so the allowee taps nothing and the allowance is active as soon as the offer arrives.

Description

• Adds automatic acceptance of a received allowance proposal that makes this wallet the allowee, so the allower's decision alone activates the allowance.
• Adds an "Allowance Added" notification, "{name} set up an allowance for you", with a toast fallback, so the allowee learns about the new allowance.
• Keeps the review sheet with Accept and Decline for an allowee's ask, because there the money is this wallet's.
• Retries a failed acceptance on the next refresh, and never touches a proposal this wallet sent or one already answered.

Out of Scope

• app/src/main/res: the new strings are English only until the next translation sync.

Design

N/A — no design available.

Preview

Payer: Set Allowance	Payer: waiting for an answer	Payer: Active

Allowee: Allowance Added notification	Allowee: notification shade	Allowee: row Active

Recording
allowance-set-and-accept-payer-left-payee-right.mp4

QA Notes

Journeys

• updated set-and-accept.xml — the allowee's wallet accepts the offer with no review sheet, posts "Allowance Added", and both rows turn Active
  • Driven on two fresh staging wallets, a3861ce build, Paykit rc59: the allowee accepted once with no tap, no review sheet opened, "Allowance Added" posted once, and both rows turned Active. The allowee's row took about 3 min 16 s after Save on a heavily loaded host, 2 min of it the payer publishing the proposal.
  • Journey drift, not edited here: the intro button has no SkipIntro tag (its "Skip Intro" text works), and Choose Contact shows "Add a contact first" for about 3 minutes after the contacts are saved, until Paykit discovery finishes.

Manual Tests

N/A

Automated Checks

• added PaykitAllowanceTest.kt — only a received proposal from the allower counts as an offer
• added PaykitAllowanceRepoTest.kt — an allower's offer is accepted without the sheet and not announced twice; a failed accept is retried; an allowee's ask still goes to the sheet; sent and answered proposals are never accepted
• updated AppViewModelSendFlowTest.kt — the send flow stubs the new acceptance call
• ran ./gradlew assembleDevDebug testDevDebugUnitTest detekt on Paykit 0.1.0-rc59 merged with feat: add allowances for automatic paykit payments #1340 (b929cce) — 3,227 unit tests pass and detekt is clean

[ovitrif]

Pushed 528fb7b: merged the updated feat/paykit-allowances (Paykit rc59, allowances bound to the contact identity) into this branch.

• The auto-accept code needed no change, since it already addresses an allowance by counterparty and allowance id.
• The new tests now use the identity-bound acceptAllowance(counterparty, allowanceId) and processOutboundPrivateMessages(counterparty) calls (a3861ce).
• The rule is unchanged: only a received proposal that makes this wallet the allowee is accepted automatically; an ask from the allowee still opens the review sheet.
• testDevDebugUnitTest (3,220 tests) and detekt pass.
• Device run of set-and-accept.xml on two emulators is still pending; screenshots and a recording follow in the description.

[ovitrif]

Added the device result and media to the description.

• set-and-accept.xml passes on two fresh staging wallets with the a3861ce build (Paykit rc59): the allowee accepted with no tap and no review sheet, "Allowance Added" posted once, and both rows turned Active.
• Save to the allowee's row took about 3 min 16 s on a heavily loaded host.
• The build was a3861ce; head 528fb7b only adds a base merge that touches PaykitAllowanceRepo.kt (one line) and PaykitPaymentRequestRepo.kt.
• Preview now has the payer and allowee screenshots plus the recording.
• Journey drift is noted under QA Notes and the journey is not edited here.

[ovitrif]

Pushed e7a8bd3: merged the updated feat/paykit-allowances (b929cce, Ben's newer shared-runtime sync and Paykit session retry) into this branch.

• The merge was clean and changes none of this PR's code.
• testDevDebugUnitTest (3,227 tests) and detekt pass on the merged head.
• The device run was on the a3861ce build, before this merge, and has not been repeated.