Fix: km config shows entire configuration, not just one node

[dluc]

Problem

km config was calling Initialize() which forced node selection, making it show only one node instead of the entire configuration.

Before:

$ km config
{
  "nodeId": "personal",    # Only showed selected node
  "access": "Full",
  ...
}

After:

$ km config
{
  "nodes": [               # Shows ALL nodes
    {
      "nodeId": "personal",
      ...
    }
  ],
  "cache": {               # Shows cache config
    "embeddingsCache": {...}
  }
}

Solution

• ConfigCommand no longer calls Initialize() (no node selection needed)
• Uses GetConfig() to access the injected config directly
• Default behavior shows entire config (all nodes + cache)
• --show-nodes and --show-cache flags still work

TDD Approach

1. ✅ Test written first (RED) - verified it failed
2. ✅ Code fixed (GREEN) - test now passes
3. ✅ All 262 tests passing (185 Main + 77 Core)

Changes

• Add ConfigCommandTests with multi-node config verification
• Update ConfigCommand to skip Initialize() for config queries
• Add BaseCommand.GetConfig() protected method

Test Results

• ✅ 262 tests passing (185 Main + 77 Core)
• ✅ Zero failures, zero skipped
• ✅ Zero regressions