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/models/__init__.py

@@ -0,0 +1,134 @@
+from __future__ import annotations
+
+from typing import Any, Dict, List, Optional
+
+from aitbc_sdk import SignatureValidation
+
+from pydantic import BaseModel
+
+
+class SignatureValidationModel(BaseModel):
+    key_id: str
+    alg: str = "Ed25519"
+    valid: bool
+
+
+class ReceiptVerificationModel(BaseModel):
+    job_id: str
+    receipt_id: str
+    miner_signature: SignatureValidationModel
+    coordinator_attestations: List[SignatureValidationModel]
+    all_valid: bool
+
+
+class ReceiptVerifyResponse(BaseModel):
+    result: ReceiptVerificationModel
+
+
+def _signature_to_model(sig: SignatureValidation | SignatureValidationModel) -> SignatureValidationModel:
+    if isinstance(sig, SignatureValidationModel):
+        return sig
+    return SignatureValidationModel(key_id=sig.key_id, alg=sig.algorithm, valid=sig.valid)
+
+
+def from_validation_result(result) -> ReceiptVerificationModel:
+    return ReceiptVerificationModel(
+        job_id=result.job_id,
+        receipt_id=result.receipt_id,
+        miner_signature=_signature_to_model(result.miner_signature),
+        coordinator_attestations=[_signature_to_model(att) for att in result.coordinator_attestations],
+        all_valid=result.all_valid,
+    )
+
+
+class ReceiptVerificationListResponse(BaseModel):
+    items: List[ReceiptVerificationModel]
+
+
+class WalletDescriptor(BaseModel):
+    wallet_id: str
+    chain_id: str
+    public_key: str
+    address: Optional[str]
+    metadata: Dict[str, Any]
+
+
+class WalletListResponse(BaseModel):
+    items: List[WalletDescriptor]
+
+
+class WalletCreateRequest(BaseModel):
+    chain_id: str
+    wallet_id: str
+    password: str
+    metadata: Dict[str, Any] = {}
+    secret_key: Optional[str] = None
+
+
+class WalletCreateResponse(BaseModel):
+    wallet: WalletDescriptor
+
+
+class WalletUnlockRequest(BaseModel):
+    password: str
+
+
+class WalletUnlockResponse(BaseModel):
+    wallet_id: str
+    chain_id: str
+    unlocked: bool
+
+
+class WalletSignRequest(BaseModel):
+    password: str
+    message_base64: str
+
+
+class WalletSignResponse(BaseModel):
+    wallet_id: str
+    chain_id: str
+    signature_base64: str
+
+
+class ChainInfo(BaseModel):
+    chain_id: str
+    name: str
+    status: str
+    coordinator_url: str
+    created_at: str
+    updated_at: str
+    wallet_count: int
+    recent_activity: int
+
+
+class ChainListResponse(BaseModel):
+    chains: List[ChainInfo]
+    total_chains: int
+    active_chains: int
+
+
+class ChainCreateRequest(BaseModel):
+    chain_id: str
+    name: str
+    coordinator_url: str
+    coordinator_api_key: str
+    metadata: Dict[str, Any] = {}
+
+
+class ChainCreateResponse(BaseModel):
+    chain: ChainInfo
+
+
+class WalletMigrationRequest(BaseModel):
+    source_chain_id: str
+    target_chain_id: str
+    wallet_id: str
+    password: str
+    new_password: Optional[str] = None
+
+
+class WalletMigrationResponse(BaseModel):
+    success: bool
+    source_wallet: WalletDescriptor
+    target_wallet: WalletDescriptor
+    migration_timestamp: str