feat(security): implement deterministic weighted posture scoring engine and service

[rabsqueen]

🎯 Core Overview

Problem Statement

Security analysts currently process high volumes of loose alert telemetry across environments, but lack a clear, single key performance indicator (KPI) summarizing an organization's overall operational security risk. This makes it difficult to track risk levels over time or flag gradual security degradation before an incident occurs.

Proposed Solution

This PR adds the core elements of the SecurityPostureScoringSystem under src/modules/security-posture/. It introduces a deterministic scoring engine that processes configurable weighted risk parameters, caps deduction vectors, and normalizes output scores on a 0–100 scale. It also includes an alert hook to catch score drops below configured thresholds.

Closes #153

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🛠️ Technical Implementation Details

1. Deterministic Calculation Architecture

• Built PostureScoreEngine with isolated pure evaluation logic. Given the same configuration arrays and inputs, the system returns identical scores, ensuring testability and compliance.

2. Fault-Isolated Processing

• Wrap factor metrics within clear try/catch error spaces. If an individual metric collector fails or returns incomplete telemetry data, the engine isolates the error, logs the context, and completes calculations for the remaining factors.

3. Metric Weights & Contribution Caps

• Supports distinct risk calculation configurations (weight coefficients and maxContribution caps) to ensure that a massive burst of minor alerts cannot completely wipe out an organization's security score on its own.

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📋 Quality Assurance Matrix

• Compilation completes cleanly under strict environment rule flags (npm run build).
• Extensible structures let teams register new factors without altering the core computation loop.
• Verified that score drops below threshold levels successfully trigger system log alert warnings.