feat: add thinking steps

[srtaalej]

Summary

This PR introduces new Thinking Steps features into Node.

Included in this PR:

• Chunks in chat.{appendStream, startStream, stopStream} methods ⭐

Code Snippet

const stream = new ChatStreamer(client, client.logger, {
      channel: CHANNEL_ID,
      thread_ts: threadTs,
      recipient_team_id: 'T09EX3FS2J3',
      recipient_user_id: 'U09G4FG3TRN',
    }, { buffer_size: 1 });

    await stream.append({
      chunks: [
        {
          type: 'markdown_text',
          text: '**Hello!** I am starting to process your request...\n\n'
        }]
    });
   
    await stream.append({
      chunks: [
        {
          type: 'plan_update',
          title: ''\nProcessing tasks...\n,
        },
        {
          type: 'task_update',
          id: 'task-1',
          title: 'Fetching data from API',
          status: 'complete',
          output: 'Successfully retrieved 42 records',
        },
        {
          type: 'task_update',
          id: 'task-2',
          title: 'Processing results',
          status: 'pending',
        },
      ],
    });
    
    await stream.append({
      chunks: [
        {
          type: 'task_update',
          id: 'task-2',
          title: 'Processing results',
          status: 'complete',
          output: 'Analysis complete!',
          sources: [
            {
              type: 'url',
              url: 'https://example.com/docs',
              text: 'Documentation',
            },
            {
              type: 'url',
              url: 'https://example.com/api',
              text: 'API Reference',
              icon_url: 'https://example.com/favicon.ico',
            },
          ],
        },
      ],
    });
   
     await stream.append({
      chunks: [
        {
          type: 'markdown_text',
          text: 'Hi Ale!\n\n',
        },
        {
          type: 'markdown_text',
          text: 'Here is what I found:\n\n',
        },
        {
          type: 'markdown_text',
          text: '- Item 1: *Important information*\n',
        },
        {
          type: 'markdown_text',
          text: '- Item 2: `Some code snippet`\n',
        },
      ],
    });

   
    await stream.stop({
      chunks: [
        {
          type: 'markdown_text',
          text: '\n\n---\n\n✅ **All tasks completed successfully!**\n',
        },
        {
          type: 'markdown_text',
          text: 'Thank you for using the streaming API with chunks.',
        },
      ],
    });

• Task and Plan Blocks for chat. methods ⭐

Code Snippet

const parentMessage = await client.chat.postMessage({
      channel: CHANNEL_ID,
      text: '🧵 Starting a streaming conversation with chunks...',
      blocks: [
        {
          type: 'plan',
          plan_id: 'plan-123',
          title: 'My Task',
          tasks: [
            {
              type: 'task_card',
              task_id: 'task-124',
              title: 'Task1',
              status: 'complete'
            },
            {
              type: 'task_card',
              task_id: 'task-125',
              title: 'task2',
              status: 'complete'
            },
          ]
        }
      ]
    });

Requirements (place an x in each [ ])

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[codecov]

Codecov Report

❌ Patch coverage is 99.31973% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 93.15%. Comparing base (e46cdd8) to head (d7a64ac).
⚠️ Report is 3 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2484      +/-   ##
==========================================
+ Coverage   93.09%   93.15%   +0.06%     
==========================================
  Files          40       40              
  Lines       11239    11359     +120     
  Branches      713      726      +13     
==========================================
+ Hits        10463    10582     +119     
- Misses        764      765       +1     
  Partials       12       12              

Flag	Coverage Δ
cli-hooks	95.23% <ø> (ø)
cli-test	94.79% <ø> (ø)
oauth	77.39% <ø> (ø)
socket-mode	61.87% <ø> (ø)
web-api	98.13% <99.31%> (+0.01%)	⬆️
webhook	96.66% <ø> (ø)

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[changeset-bot]

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