Fix license headers and add comprehensive documentation for claim pallet

[Copilot]

Replaced incorrect Polkadot GPL license headers with Robonomics Apache 2.0 license and added missing documentation for the Ethereum-to-Substrate claim pallet.

Changes

License Headers

• Updated all source files (lib.rs, benchmarking.rs, mock.rs, tests.rs) to use Robonomics Apache 2.0 license instead of Polkadot GPL

In-Code Documentation

• Added module-level documentation explaining pallet purpose, features, and usage patterns
• Documented all Config trait parameters with context (e.g., Prefix for signature replay protection, PalletId for account derivation)
• Added function documentation with parameter descriptions and error conditions
• Documented helper functions (ethereum_signable_message, eth_recover, process_claim) and test utilities

README.md

Created comprehensive user-facing documentation including:

• Configuration examples with runtime setup
• Complete claim flow with code examples for web3.js, ethers.js, and MetaMask
• Governance operations (adding claims, funding pallet account)
• Architecture details (storage, extrinsics, events)
• Security considerations (signature format, replay protection, one-time claims)
• Troubleshooting guide for common issues

All code examples correctly demonstrate signing with the configured prefix prepended to the account ID.

Example usage from README:

// Sign destination account with Ethereum key (including prefix)
const accountBytes = api.createType('AccountId', destinationAccount).toU8a();
const accountHex = u8aToHex(accountBytes, -1, false);
const prefix = 'Pay RWS to the Robonomics account:';
const message = prefix + accountHex;
const signature = await wallet.signMessage(message);

// Submit claim
await api.tx.claims.claim(destinationAccount, signature).send();

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[akru]

@copilot dont forget about Prefix in examples.

[Copilot]

@copilot dont forget about Prefix in examples.

Fixed in commit 107e097. Updated all code examples to include the prefix when signing messages:

const prefix = 'Pay RWS to the Robonomics account:';
const message = prefix + accountHex;
const signature = await wallet.signMessage(message);

The examples now correctly show that users must construct the message as {Prefix}{hex_account_id} before signing, and explain that personal_sign automatically adds the Ethereum message wrapper.