Fix unit issues in balance/transfer actions

[phdargen]

Description

Fixes issues for native/erc20 balance actions reported by @Story91:

• get_wallet_details returns ETH amount in wei, LLM converts this to whole units in message to user. Result of conversion depends on LLM knowledge, gpt-4o-mini always got it wrong in my tests
  -> get_wallet_details returns now both amount in wei and whole units

• when several erc20 token balances are queried in one prompt, default rpc might throw error due to rate limits
  -> made rpc calls more efficient using multicall

• when prompting eg "fetch usdc balance", LLM often hallucinates address (for example taking usdc address from mainnet, not base)
  -> refined action description + added new action to retrieve commonly used token addresses by symbol for given network

In addition, the following improvements are made:

• WalletActionProvider native_transfer takes amount in whole units as input and passes this to walletProviders. However, most of them expect atomic units instead -> this is now handled consistently as follows: action takes whole unit format as input, converts to atomic units and then calls internal native_transfer from walletProviders with that
• remove hardcoded erc20 abi in favor of viem export
• added guardrails for erc20 transfers to prevent loss of funds by sending to token contracts
• added optional address arg (default to wallet address) to get_balance erc20 action
• fixed examples/langchain-cdp-chatbot /chatbot.ts to correctly configure CdpSolanaWalletProvider
• fixed native sol transfers for CdpSolanaWalletProvider that was throwing Error during transfer: Error: Signature must be 64 bytes long

Tests

Chatbot: typescript/examples/langchain-cdp-chatbot/chatbot.ts
Network: Base mainnet

Prompt: wallet info

-------------------
Wallet Details:
- Provider: cdp_evm_wallet_provider
- Address: 0xf2d4580ADfe8E012f5550322706d62DF11fDBE21
- Network:
  * Protocol Family: evm
  * Network ID: base-mainnet
  * Chain ID: 8453
- Native Balance: 411444858090719 WEI
- Native Balance: 0.000411444858090719 ETH
-------------------
Here are the details of your wallet:

- **Address:** 0xf2d4580ADfe8E012f5550322706d62DF11fDBE21
- **Provider:** cdp_evm_wallet_provider
- **Network:**
  - **Protocol Family:** EVM
  - **Network ID:** base-mainnet
  - **Chain ID:** 8453
- **Native Token Balance:** 0.000411444858090719 ETH
-------------------

Prompt: fetch usdc and cbbtc balance

-------------------
Token address for USDC on base-mainnet: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
-------------------

-------------------
Balance of USD Coin (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) at address 0xf2d4580ADfe8E012f5550322706d62DF11fDBE21 is 0.231121
-------------------
Here are your balances for USDC and CBBTC:

- **USDC Balance:** 0.231121 USDC
- **CBBTC Balance:** 0.00000024 CBBTC

If you need any further assistance, let me know!
-------------------

Prompt: check bankr balance

-------------------
Error: Token symbol "BANKR" not found on base-mainnet. Available token symbols on base-mainnet: USDC, EURC, CBBTC, CBETH, WETH, ZORA, AERO, BNKR, CLANKER
-------------------

-------------------
Token address for BNKR on base-mainnet: 0x22af33fe49fd1fa80c7149773dde5890d3c76f3b
-------------------

-------------------
Balance of BankrCoin (0x22af33fe49fd1fa80c7149773dde5890d3c76f3b) at address 0xf2d4580ADfe8E012f5550322706d62DF11fDBE21 is 0
-------------------
Your balance for BankrCoin (BNKR) is **0**. If you need assistance with anything else, feel free to ask!
-------------------

Prompt: send 0.001 usdc to 0xa8c1a5D3C372C65c04f91f87a43F549619A9483f
Transferred 0.001 of USD Coin (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) to 0xa8c1a5D3C372C65c04f91f87a43F549619A9483f.
Transaction hash for the transfer: 0xfc070337f72b5e154e556d007efc6418ff8c74bcc29c087107e07efdcc16daf2
-------------------
I have successfully transferred **0.001 USDC** to the address **0xa8c1a5D3C372C65c04f91f87a43F549619A9483f**. 

The transaction hash is: **0xfc070337f72b5e154e556d007efc6418ff8c74bcc29c087107e07efdcc16daf2**.

If you need anything else, just let me know!
-------------------

Prompt: send 0.000001 eth to 0xa8c1a5D3C372C65c04f91f87a43F549619A9483f

-------------------
Transferred 0.000001 ETH to 0xa8c1a5D3C372C65c04f91f87a43F549619A9483f
Transaction hash: 0xeafcac9aa1beb05a2dd72362741939287b6b951ef70a96de38252d5270b08221
-------------------
I have successfully transferred **0.000001 ETH** to the address **0xa8c1a5D3C372C65c04f91f87a43F549619A9483f**.

The transaction hash is: **0xeafcac9aa1beb05a2dd72362741939287b6b951ef70a96de38252d5270b08221**.

Prompt: check usdc balance for 0xa8c1a5D3C372C65c04f91f87a43F549619A9483f

----------
Balance of USD Coin (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) at address 0xa8c1a5D3C372C65c04f91f87a43F549619A9483f is 9.076885
-------------------
The balance of USDC for the address **0xa8c1a5D3C372C65c04f91f87a43F549619A9483f** is **9.076885 USDC**.

Chatbot: typescript/examples/langchain-cdp-chatbot/chatbot.ts
Network: Solana devnet

Prompt: send 0.0001 sol to 91sEBA6DLKakGV4raqW2pE8bmQR1D9dnbdGTjtATur5U 

-------------------
Transferred 0.0001 SOL to 91sEBA6DLKakGV4raqW2pE8bmQR1D9dnbdGTjtATur5U
Signature: 45MJKkm5CEQbCED8s7Ykz8P8bFySyqXq8AoLWzXW2NXUMMWwW2hcUs22yux1M9q5RHvcUGvcVbgHyy3sHGVC6CyM
-------------------
The transfer of 0.0001 SOL to the address **91sEBA6DLKakGV4raqW2pE8bmQR1D9dnbdGTjtATur5U** has been successfully completed. 

Transaction Signature: **45MJKkm5CEQbCED8s7Ykz8P8bFySyqXq8AoLWzXW2NXUMMWwW2hcUs22yux1M9q5RHvcUGvcVbgHyy3sHGVC6CyM**

Checklist

A couple of things to include in your PR for completeness:

• Added documentation to all relevant README.md files
• Added a changelog entry

[cb-heimdall]

✅ Heimdall Review Status

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[CarsonRoscoe]

Fantastic work, ty! Lots of little chores we've been meaning to get to all wrapped up in one nice package