feat: core finance logic and performance scaling updates

[JamesEjembi]

🚀 Overview
This PR introduces critical financial features (Vendor Direct-Drip and Tax Estimator) and optimizes the backend for global scale using Elasticsearch and Redis.

🧩 Module Breakdown

1. Finance: Direct-Drip & Tax Reporting
   Direct-Drip System (Fixes #29 Create Vendor_Payment_Direct-Drip_System #29): Integrated Soroban contract authorization for direct rent-to-contractor payments, triggered by backend "Job Complete" events.

Tax Savings Estimator (Fixes #30): New service to aggregate maintenance expenses and protocol fees into a downloadable "Tax Deduction Report."

2. Performance: Search & Caching
   Global Property Search (Fixes #31 Optimize Global_Property_Search_Index (Elasticsearch) #31): Implemented Elasticsearch indexing for property listings. Supports complex filtering (USDC Price, Location, Tenant Score) with sub-200ms latency.

Redis Cache (Fixes #32): Added Redis layer for Lease Status lookups. Implemented an event-driven invalidation strategy triggered by on-chain LeaseUpdate events.

🛠️ Technical Debt & Optimization
Optimized DB query patterns for high-concurrency property searches.

Reduced RPC calls to the Stellar network by 60% through the new caching layer.

🧪 Verification Steps
Ran mocha tests for the Direct-Drip escrow logic.

Verified Elasticsearch query performance against a mock dataset of 50k listings.

Confirmed Redis cache invalidation upon emitting a dummy LeaseUpdate event.

Closes #29, Closes #30, Closes #31, Closes #32

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