feat: configurable native token metadata (on-chain, API, CLI)

[spreston8]

Summary

Adds configurable native token identity (name, symbol, decimals) that is baked into an on-chain Rholang contract at genesis and exposed via the node's API.

• New TokenMetadata Rholang contract deployed at genesis, registered at rho:system:tokenMetadata with nonce i64::MAX (immutable)
• Three new config fields in defaults.conf under casper.genesis-block-data: native-token-name (F1R3CAP), native-token-symbol (F1R3), native-token-decimals (8)
• Three new CLI flags: --native-token-name, --native-token-symbol, --native-token-decimals (decimals capped at 18, empty/whitespace rejected)
• /api/status and gRPC Status response include nativeTokenName, nativeTokenSymbol, nativeTokenDecimals
• Joiner nodes verify config matches on-chain values at startup; mismatch causes clean exit with structured error event
• All startup paths (ceremony master, genesis validator, joiner, observer) log the effective token metadata
• Compose files parameterized with env var overrides per node

Closes #477

Files changed (41)

New:

• casper/src/main/resources/TokenMetadata.rhox — Rholang contract with 4 methods (name, symbol, decimals, all)
• casper/src/rust/util/token_metadata_check.rs — on-chain verification + structured logging
• casper/src/test/resources/TokenMetadataTest.rho — contract test
• casper/tests/genesis/contracts/token_metadata_spec.rs — Rust test wrapper

Modified: config structs, genesis pipeline, API layer, compose files, docs

Test plan

• cargo check --workspace --tests passes (0 warnings)
• cargo test --release -p node — 108 passed, 0 failed
• Smoke test against local shard — 30/30 passed
• Integration tests (test_token_metadata.py) — 18/18 passed in ~2 min (6 parallel workers)
• CI on rust/staging

Co-Authored-By: Claude noreply@anthropic.com