refactor: consolidate blockchain explorer into single app and update backup ignore patterns

- Remove standalone explorer-web app (README, HTML, package files)
- Add /web endpoint to blockchain-explorer for web interface access
- Update .gitignore to exclude application backup archives (*.tar.gz, *.zip)
- Add backup documentation files to .gitignore (BACKUP_INDEX.md, README.md)
- Consolidate explorer functionality into main blockchain-explorer application

apps/wallet/src/app/receipts/__init__.py

@@ -0,0 +1,5 @@
+"""Receipt verification helpers for the wallet daemon."""
+
+from .service import ReceiptValidationResult, ReceiptVerifierService
+
+__all__ = ["ReceiptValidationResult", "ReceiptVerifierService"]

apps/wallet/src/app/receipts/service.py

@@ -0,0 +1,58 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import List, Optional
+
+from aitbc_sdk import (
+    CoordinatorReceiptClient,
+    ReceiptVerification,
+    SignatureValidation,
+    verify_receipt,
+    verify_receipts,
+)
+
+
+@dataclass
+class ReceiptValidationResult:
+    job_id: str
+    receipt_id: str
+    receipt: dict
+    miner_signature: SignatureValidation
+    coordinator_attestations: List[SignatureValidation]
+
+    @property
+    def miner_valid(self) -> bool:
+        return self.miner_signature.valid
+
+    @property
+    def all_valid(self) -> bool:
+        return self.miner_signature.valid and all(att.valid for att in self.coordinator_attestations)
+
+
+class ReceiptVerifierService:
+    """Wraps `aitbc_sdk` receipt verification for wallet daemon workflows."""
+
+    def __init__(self, coordinator_url: str, api_key: str, timeout: float = 10.0) -> None:
+        self.client = CoordinatorReceiptClient(coordinator_url, api_key, timeout=timeout)
+
+    def verify_latest(self, job_id: str) -> Optional[ReceiptValidationResult]:
+        receipt = self.client.fetch_latest(job_id)
+        if receipt is None:
+            return None
+        verification = verify_receipt(receipt)
+        return self._to_result(verification)
+
+    def verify_history(self, job_id: str) -> List[ReceiptValidationResult]:
+        receipts = self.client.fetch_history(job_id)
+        verifications = verify_receipts(receipts)
+        return [self._to_result(item) for item in verifications]
+
+    @staticmethod
+    def _to_result(verification: ReceiptVerification) -> ReceiptValidationResult:
+        return ReceiptValidationResult(
+            job_id=str(verification.receipt.get("job_id")),
+            receipt_id=str(verification.receipt.get("receipt_id")),
+            receipt=verification.receipt,
+            miner_signature=verification.miner_signature,
+            coordinator_attestations=list(verification.coordinator_attestations),
+        )