feat(cost): add AWS Cost Explorer automation documents

[somethingwithproof]

Description

Add AWS Cost Explorer automation documents for cost optimization.

Motivation

• Automate cost anomaly detection
• Generate scheduled cost reports
• Identify unused resources automatically
• Support FinOps practices

Proposed Solution

1. Create SSM document for cost analysis
2. Add unused resource detection (EBS, EIP, snapshots)
3. Implement rightsizing recommendations
4. Generate cost allocation reports

Acceptance Criteria

• Cost anomaly detection automation
• Unused EBS volume identification
• Unattached EIP cleanup
• Stale snapshot identification
• Weekly cost summary reports
• Rightsizing recommendations export

SSM Document Structure

schemaVersion: '2.2'
description: 'Cost optimization analysis'
parameters:
  AccountId:
    type: String
  ReportBucket:
    type: String
mainSteps:
  - action: 'aws:executeScript'
    name: analyzeUnusedResources
    inputs:
      Runtime: python3.9
      Handler: analyze_costs

Commits should follow

feat(cost): add unused EBS volume detection
feat(cost): implement EIP cleanup automation
feat(reports): add weekly cost summary generation