Implement RECEIPT_CLAIM transaction type

- Add status fields to Receipt model (status, claimed_at, claimed_by)
- Add RECEIPT_CLAIM handling to state_transition.py with validation and reward minting
- Add type field to Transaction model for reliable transaction type storage
- Update router to use TransactionRequest model to preserve type field
- Update poa.py to extract type from mempool transaction content and store only original payload
- Add RECEIPT_CLAIM to GasType enum with gas schedule

examples/node.env.example

@@ -6,17 +6,19 @@
 # Node Identity
 # =========================
 # Unique identifier for this node (must be different for each node)
-NODE_ID=aitbc
+NODE_ID=node-<unique-uuid-here>
 
 # =========================
 # P2P Configuration
 # =========================
 # P2P node identity (must be unique for each node)
-p2p_node_id=aitbc
+# Auto-generated by setup.sh, or generate manually: node-$(uuidgen | tr -d '-')
+p2p_node_id=node-<unique-uuid-here>
 
 # Proposer ID (PoA authority/block proposer)
 # Each node should have its own unique proposer_id
-proposer_id=ait1ytkh0cn8v2a4zjwzyav6854832myf9j7unsse8yntmuwzst4qhtqe9hqdw
+# Auto-generated by setup.sh, or generate manually: ait1$(uuidgen | tr -d '-')
+proposer_id=ait1<unique-uuid-here>
 
 # Set false on follower/non-proposer nodes
 # enable_block_production=false