feat: Four market backend enhancements

[Emmy6654]

Closes #1073
Closes #1074
Closes #1075
Closes #1076

Summary

Implements four backend enhancements for the BOXMEOUT market service:

1. Fallback reconciliation from Soroban RPC (Task 1)

• reconcileMarketFromChain(marketId) reads market state directly from on-chain via simulateTransaction calling get_market_info()
• Properly builds a TransactionBuilder with a throwaway keypair for read-only simulation
• Parses Soroban ScVal return values using scValToNative
• Maps on-chain status/pools/outcome to DB columns and overwrites the row
• Admin endpoint: POST /api/admin/markets/:id/reconcile (adminAuth-protected)
• Used when cached data is suspected stale (force refresh action)

2. Optimistic row insertion on create_market tx (Task 2)

• createMarketOptimistic(txHash, marketData) inserts an optimistic row immediately after tx submission
• Uses txHash as temporary ID so row can be matched when the real event arrives
• createMarketRecord() now runs an interactive Prisma transaction to atomically reconcile:
  1. Finds optimistic row by txHash inside the transaction
  2. Deletes optimistic row and creates the real one with on-chain market_id
  3. Falls back to standard upsert if no optimistic row exists
• Zod validation on the POST /api/markets/optimistic endpoint
• No duplication: matched by txHash; race-condition safe via interactive transaction

3. List markets created by a given address (Task 3)

• getMarketsByCreator(createdBy, pagination) uses indexed createdBy column
• Returns { data: Market[], total: number } with page/limit pagination
• Added @@index([createdBy]) on the Market model
• Migration: CREATE INDEX Market_createdBy_idx ON Market (createdBy)
• Endpoint: GET /api/markets/by-creator/:address?page=&limit=
• No full table scan — query uses B-tree index

4. Single-market lookup by marketId (Task 4)

• getMarketById() returns Market | null for unknown IDs (not a thrown error)
• Controller returns 404 for null results
• Cleaned up merge conflict artifacts in market.service.ts:
  • Removed duplicate imports
  • Consolidated getAllMarkets, getMarketById, createMarketRecord
  • Switched from raw PrismaClient to shared db instance

Files Changed

File	Change
backend/src/services/market.service.ts	Cleanup + all 4 new functions
backend/src/api/controllers/market.controller.ts	3 new handlers + Zod validation
backend/src/api/routes/market.routes.ts	3 new routes + cleanup duplicates
backend/prisma/schema.prisma	@@index([createdBy]) on Market
backend/prisma/migrations/.../migration.sql	New index migration

Testing

• TypeScript compilation: no errors in changed files
• Indexer service tests: 33/33 pass