Bootstrap copied BFF and local accounts with public Sendico contracts (#34)

backend/contracts/sendico/models/wallet/wallet_asset.yaml

@@ -0,0 +1,19 @@
+components:
+  schemas:
+    WalletAsset:
+      description: Canonical managed-wallet asset identified by chain, token symbol, and optional contract address.
+      type: object
+      additionalProperties: false
+      required:
+        - chain
+        - tokenSymbol
+      properties:
+        chain:
+          description: Canonical blockchain network for the asset.
+          $ref: ../../external/chain_network.yaml#/components/schemas/ChainNetwork
+        tokenSymbol:
+          description: Upper-case asset symbol.
+          type: string
+        contractAddress:
+          description: Normalized contract address for token assets. Omitted for native assets.
+          type: string