[Joel234-png]

Closes #1367
Closes #1368
Closes #1402

… (#1402, #1368, #1367)

#1402 B-104: Verify POST /api/markets against the chain instead of trusting client fields

• MarketVerificationService to validate markets exist on-chain before registration
• Prevents users from registering fake market records that don't exist on-chain
• Verifies contract address format (valid Stellar account)
• Queries Soroban RPC to confirm market exists at provided contract
• Validates client-provided metadata matches on-chain data
• Rejects if client tries to override immutable chain data
• Prevents creator spoofing by validating against authenticated user
• Only indexer should create real market records via chain events

#1368 C-110: Snapshot-test ContractError discriminants shared with the frontend

• Added comprehensive snapshot tests in errors.test.rs
• Tests pin numeric error codes that frontend maps to error messages
• Verifies all 23 error codes match snapshot (1, 2, 3, 10-15, 20-23, 30-32, 40-42, 50-52, 60)
• Tests for uniqueness: no duplicate error codes
• Tests for range integrity: proper organization by category with no overlaps
• Failure message explicitly warns: "DO NOT CHANGE ERROR CODES - they are part of the contract API"
• Documents that frontend/lib/errors.ts must be updated if codes change
• Prevents silent frontend breakage from reordering or renumbering errors

#1367 C-109: Constrain Treasury::emergency_drain with timelock, events, and escrow protection

• Implements 48-hour timelock before drain can execute
• Prevents instant theft by requiring proposal → wait → execute pattern
• Validates recipient against pre-approved emergency whitelist
• Protects escrowed funds for open markets (cannot drain committed user funds)
• Rate limiting: maximum 20% drain per 24-hour period
• Comprehensive audit logging of all proposals and executions
• Amount validation and re-checking before execution
• Period-based rate limiting that resets every 24 hours
• Cancel proposal function for admin control
• Emits events for all drain operations for blockchain audit trail