Add ERC20 approve and allowance functionality

[0xgeorgemathew]

Add ERC20 approve and allowance functionality

Adds two new methods to the ERC20 action provider:

1. approve(): Enables token approval for spenders
2. getAllowance(): Checks spender allowances

Changes

• TypeScript implementation with error handling
• Corresponding zod schemas
• Documentation for both methods

Review Focus

• Error handling robustness
• Schema validation completeness
• Transaction wait for approval confirmation
• Documentation clarity

This enhances token management by supporting delegation of spending rights.

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1

[John-peterson-coinbase]

@0xgeorgemathew - Please add tests and chatbot chat snippets of the actions being used with the example agent to the PR description. Otherwise LGTM 🚀