Fix: km config output matches AppConfig structure

[dluc]

Problem

km config output used DTOs with different structure than the actual AppConfig format, making it impossible for users to copy/paste output back into their config file.

Before (wrong structure):

{
  "nodes": [               // ❌ Array (wrong!)
    {
      "nodeId": "personal",
      ...
    }
  ],
  "cache": {               // ❌ Wrong property name
    "embeddingsCache": {...}
  }
}

After (correct structure):

{
  "nodes": {               // ✅ Object/Dictionary (correct!)
    "personal": {
      "id": "personal",
      ...
    }
  },
  "embeddingsCache": {    // ✅ At root level (correct!)
    ...
  }
}

Solution

• ConfigCommand default output is now this.Config (actual AppConfig object)
• Users can now copy/paste the output directly into their config file
• --show-nodes and --show-cache flags still use DTOs (unchanged)

TDD Approach

1. ✅ Test written first (RED) - verified structure mismatch
2. ✅ Code fixed (GREEN) - output now matches AppConfig
3. ✅ All validation scripts pass

Changes

• Update ConfigCommand to output actual AppConfig (not DTOs)
• Add test verifying output structure matches config file format
• Add embeddingsCache to test fixture for complete validation

Definition of Done

• Test written first (TDD approach)
• ./build.sh passes - 0 warnings, 0 errors
• ./format.sh passes
• ./coverage.sh passes - 81.64% coverage (>80% minimum)
• All 263 tests passing (186 Main + 77 Core)
• Zero skipped tests