fix(backend): Improve typing for blocks StepThroughItemsBlock, CountdownTimerBlock, AddToListBlock, AddToDictionaryBlock

[majdyz]

This addresses #8679 & #8676

Some list & dictionary blocks mix the types with None or other types, making the input rendered as an any / free-text input field instead of proper array & key-value input.

Changes 🏗️

Improve typing for blocks StepThroughItemsBlock, CountdownTimerBlock, AddToListBlock, AddToDictionaryBlock

Checklist 📋

For code changes:

• I have clearly listed my changes in the PR description
• I have made a test plan
• I have tested my changes according to the test plan:
  • ...

Example test plan

• Create from scratch and execute an agent with at least 3 blocks
• Import an agent from file upload, and confirm it executes correctly
• Upload agent to marketplace
• Import an agent from marketplace and confirm it executes correctly
• Edit an agent from monitor, and confirm it executes correctly

For configuration changes:

• .env.example is updated or already compatible with my changes
• docker-compose.yml is updated or already compatible with my changes
• I have included a list of my configuration changes in the PR description (under Changes)

Examples of configuration changes

• Changing ports
• Adding new services that need to communicate with each other
• Secrets or environment variable changes
• New or infrastructure changes such as databases

[qodo-merge-pro]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 PR contains tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Code Duplication The items, items_object and items_str fields in StepThroughItemsBlock seem to serve the same purpose with different types. Consider consolidating these into a single field that handles type conversion internally. Potential Bug The AddToListBlock's run method uses entries_added before checking if input_data.entry exists, which could lead to unexpected behavior if entry is None.

[netlify]

✅ Deploy Preview for auto-gpt-docs canceled.

Name	Link
🔨 Latest commit	1e1c568
🔍 Latest deploy log	https://app.netlify.com/sites/auto-gpt-docs/deploys/673cf9c6ae54fb0008d7b633