[Backend] Goal Analytics Computation `GET /goals`

[Olowodarey]

Background & Context: Render massive overarching metrics analyzing "how close" physically users are mapped against deadlines dictating color coded logic.
Description: Return goal mapping evaluating percentage bounds combining target metrics against underlying connected vaults cleanly.
Acceptance Criteria:

• Gather DB goals.
• Mathematically correlate connected live Soroban balances dictating specific progression completion attributes (percentageComplete: 74%).
  Target Files: backend/src/modules/savings/savings.service.ts.