Refactor: Create Contextual System Prompts for Tool Categories

[CocDap]

📋 Overview
Currently, the Polkadot Agent Kit uses a single monolithic system prompt that covers all operations. This makes it difficult to maintain, customize, and provide context-specific guidance for different tool categories.

🎯 Objective
Create category-specific system prompts that provide focused guidance for each tool category, improving AI assistant accuracy and maintainability.

✨ Proposed Refactor

1. Balance Operations
   Tools: check_balance

const BALANCE_SYSTEM_PROMPT = `
BALANCE OPERATIONS:
- Check native token balances across Polkadot ecosystem chains
- Support for Polkadot, Kusama, Westend, Rococo networks
- Automatic chain initialization if needed
- Clear balance reporting with token symbols
`;

2. Transfer Operations
   Tools: transfer_native, xcm_transfer_native_asset

const TRANSFER_SYSTEM_PROMPT = `
TRANSFER OPERATIONS:
- Native token transfers within the same chain
- Cross-chain transfers using XCM protocol
- Chain name conversion rules for XCM
- Address validation and amount formatting
`;

3. Staking Operations
   Tools: join_pool, bond_extra, unbond, withdraw_unbonded, claim_rewards

const STAKING_SYSTEM_PROMPT = `
STAKING OPERATIONS:
- Join nomination pools for staking rewards
- Bond additional tokens to existing pools
- Unbond tokens with withdrawal periods
- Withdraw unbonded tokens after cooling period
- Claim accumulated staking rewards
- Automatic pool membership detection
`;

4. Swap Operations
   Tools: swap_tokens

const SWAP_SYSTEM_PROMPT = `
SWAP OPERATIONS:
- Cross-chain token swapping via Hydration DEX
- DEX-specific swaps within single chains
- Chain name conversion (PascalCase for swaps)
- Token symbol validation
- Slippage tolerance configuration
`;