feat(mainnet): add Crystal MON/USDC market

[dak-agent]

Adds the Crystal MON/USDC spot market to mainnet/crystal.jsonc. Follow-up to #486.

• MON/USDC Market: 0x39fAE95717cfD4bdA22317F1c124660A166b6BEc

Verification

• Listed on Deployed Market Parameters as the MON/USDC market address.
• On-chain: deployed by the Crystal router (0x508254c838B2e936B0631440c5C6E3AB3a4a98BD) and verified on BlockVision (verifyStatus: perfect).
• baseAsset() returns 0x3bd359C1119dA7Da1D913D1C4D2B7c461115433A (WMON). quoteAsset() returns 0x754704Bc059F8C67012fEd69BC8A327a5aafb603 (USDC). Both match the docs.
• python scripts/validate_protocol.py --network mainnet passes locally.

[github-actions]

Contract Verification Results

Changed Files

• mainnet/crystal.jsonc

Verification Output

Verifying 1 protocol file(s)...

  ✓ Crystal (2 addresses)

================================================================================
                         CONTRACT VERIFICATION RESULTS                          
================================================================================

✓ Crystal (crystal.jsonc)

================================================================================
                                    SUMMARY                                     
================================================================================
  Files Processed:     1
  Addresses Checked:   2
  ✓ Verified:          2
  ✗ Not Verified:      0

  All contracts verified successfully!
================================================================================

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_{Workflow run: Verify PR Contracts}