Split lending pool contract into read/write segregated modules

[Smartdevs17]

Context

Lending pool contract mixes read and write operations.

Current Limitation

Read and write operations are not separated.

Expected Outcome

• Read-only query functions
• Write-only state modification
• Gas optimization for reads
• Parallel read execution

Acceptance Criteria

• Read-only query functions
• Write-only state modification
• Gas optimization for reads
• Parallel read execution
• Read/write access control
• Read/write testing separation
• Read/write documentation

Technical Scope

• stellar-lend/contracts/hello-world/src/lib.rs - Main contract
• stellar-lend/contracts/hello-world/src/views.rs - Read operations
• stellar-lend/contracts/hello-world/src/operations.rs - Write operations
• tests/ - Read/write tests