QVAC-13595 feat[api]: Add Bergamot pivot translation support

[RamazTs]

🎯 What problem does this PR solve?

• Enables pivot translation through intermediate languages using Bergamot models
• Allows translations between language pairs without direct models (e.g., Spanish to Italian via English)
• Extends SDK translation capabilities for more language combinations

📝 How does it solve it?

• Adds pivotModel configuration to Bergamot translation config schema
• Implements pivot model loading and path resolution in nmtcpp plugin
• Updates dependency to @qvac/translation-nmtcpp@0.6.1 for pivot support
• Includes complete example demonstrating Spanish → English → Italian translation

🧪 How was it tested?

• Created translation-bergamot-pivot.ts example with full pivot translation workflow
• Example demonstrates loading both primary and pivot models with proper configuration

🔌 API Changes

// New pivot translation API usage
await loadModel({
  modelSrc: BERGAMOT_ES_EN,  // Primary: Spanish → English
  modelType: "nmt",
  modelConfig: {
    engine: "Bergamot",
    from: "es",
    to: "it",  // Final target language
    // New pivotModel configuration
    pivotModel: {
      modelSrc: BERGAMOT_EN_IT,  // Pivot: English → Italian
      beamsize: 4,
      temperature: 0.3,
      topk: 100,
      normalize: 1,
      lengthpenalty: 1.2,
    }
  }
});

[RamazTs]

/review

[github-actions]

Tier-based Approval Status

**PR Tier:** TIER1

**Current Status:** ✅ APPROVED

**Requirements:**
- 1 Team Member approval ❌ (0/1)
- 1 Team Lead OR Management approval ✅ (2/1)

**Bypass rule:** Triggered (2+ Team Lead approvals (Tier 1 exception)). This PR is approved regardless of tier.

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*This comment is automatically updated when reviews change.*

[RamazTs]

/review