feat: Gmail read and Drive comments commands

[shahariaazam]

Summary

Adds two powerful new commands for reading email content and listing Google Drive comments.

New Features

1. Gmail Read Command

gscli gmail read <message-id>

Features:

• Read full email content by message ID
• Shows subject, from, to, date, and full body
• Supports both plain text and HTML emails
• Extracts body from multipart messages
• Beautiful formatted output
• Supports --account flag for multi-account

Example Output:

📧 Email Message

Subject: Project Update - Q4 2025
From: boss@example.com
To: me@gmail.com
Date: Nov 6, 2025, 10:30 AM
ID: 19a54d752ef22a03
Thread ID: 19a54d752ef22a03

Body:
────────────────────────────────────────────────────────────────────────────────
Hi team,

Here's the project update...

[Full email body displayed here]
────────────────────────────────────────────────────────────────────────────────

2. Google Drive Comments Command

gscli drive comments <file-id>
gscli drive comments <file-id> --include-resolved

Features:

• List comments on Google Drive files (Docs, Sheets, Slides)
• Shows unresolved comments by default
• --include-resolved flag to show all comments
• Displays author, content, creation date
• Shows comment replies
• Shows quoted content from document
• Status badges: [OPEN] or [RESOLVED]
• Supports --account flag for multi-account

Example Output:

💬 Comments on: Project Plan.docx
Found 3 comment(s)

1. John Doe [OPEN]
   Created: Nov 5, 2025, 02:30 PM
   Quoted: "We need to finalize the budget by end of week"
   Can we get this done by Friday?
   
   Replies (2):
     • Jane Smith: Yes, working on it now
     • John Doe: Thanks!

2. Alice Brown [RESOLVED]
   Created: Nov 4, 2025, 10:00 AM
   The timeline looks good

Use Cases

For AI Agents

• Read full email content for better context understanding
• Extract email bodies for summarization
• Track document feedback and comments
• Filter active discussions vs resolved issues

For Developers

• Quick email reading from terminal
• Review document comments without opening browser
• Script-friendly comment tracking
• Multi-account support for work/personal separation

Usage Examples

# Get message ID from list command
gscli gmail list --limit 5
# Copy the message ID

# Read the full email
gscli gmail read 19a54d752ef22a03

# List document comments
gscli drive comments 1abc...xyz

# Include resolved comments
gscli drive comments 1abc...xyz --include-resolved

# Use specific account
gscli gmail read 19a54d752ef22a03 --account work@company.com
gscli drive comments 1abc...xyz --account personal@gmail.com

Technical Details

Gmail Read

• Uses Gmail API messages.get with format=full
• Base64 decodes message body
• Handles multipart MIME messages
• Prefers plain text over HTML
• Falls back to snippet if body not available

Drive Comments

• Uses Drive API comments.list
• Filters resolved comments by default
• Includes comment replies in response
• Shows quoted file content
• Supports all Google Workspace file types

Testing

• ✅ TypeScript compilation passes
• ✅ Help commands updated
• ✅ --account flag works on both commands
• ✅ README and CHANGELOG updated