Add LitVM (LiteForge) testnet network support
- Register litvm_liteforge network (chain 4441, gas token zkLTC)
- LITVM_LITEFORGE_* config block (PoX, ImageRegistry, HeartBeat, RPC, integration image ecld-pynithy-litvm-testnet)
- Improve SGX-enabled log line to include network name + type
Validated on a node: resolves on-chain image QmdWfAXRjwnUfqiz56zcxHvkQaYj3zwTUY2Lf4skpUfGcb, runs integration test, passes SGX attestation.