feat: add chain-spec-tool and usdt-bridge utilities

chain-spec-tool:
- CLI utility for chain spec manipulation and validation
- Used for mainnet chain spec generation and verification

usdt-bridge:
- Custodial bridge for wUSDT token operations
- Handles USDT wrapping/unwrapping between external chains and Asset Hub
- Configuration in bridge_config.json

tools/chain-spec-tool/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "chain-spec-tool"
+version = "0.1.0"
+edition = "2021"
+description = "CLI tool for adding teyrchains to relay chain spec"
+license = "GPL-3.0-only"
+
+[workspace]
+
+[[bin]]
+name = "chain-spec-tool"
+path = "src/main.rs"
+
+[dependencies]
+anyhow = "1.0"
+clap = { version = "4.5", features = ["derive"] }
+serde = { version = "1.0", features = ["derive"] }
+serde_json = { version = "1.0", features = ["arbitrary_precision"] }