Add meaningful title validation for issue creation

[Copilot]

This PR enhances the GitHub MCP Server's issue creation functionality by implementing comprehensive title validation to ensure issues have meaningful, substantive titles rather than placeholder text.

Problem

The existing validation only checked for empty titles, allowing users to create issues with placeholder text like "Title", "TODO", or meaningless content like "!!!" or "Hi". This led to low-quality issues that don't provide clear information about the problem or request.

Solution

Added a new RequiredMeaningfulTitle validation function that enforces:

• Minimum length: Titles must be at least 3 characters long
• Content validation: Must contain at least one letter or number (not just special characters)
• Placeholder detection: Rejects common placeholder patterns like "title", "todo", "test", "untitled", etc. (case-insensitive)

Example

// Before: These would all pass validation
"" // ❌ Empty (already caught)
"Hi" // ❌ Now caught: too short
"!!!" // ❌ Now caught: no alphanumeric characters
"Title" // ❌ Now caught: placeholder text
"TODO" // ❌ Now caught: placeholder text

// After: Only meaningful titles pass
"Fix authentication bug" // ✅ Valid
"Add user dashboard" // ✅ Valid
"Bug in login system" // ✅ Valid

Changes

• Added RequiredMeaningfulTitle function in pkg/github/server.go
• Updated CreateIssue to use the enhanced validation
• Added comprehensive test coverage for all validation scenarios
• Updated README documentation to reflect the new requirements
• Maintained backward compatibility for all legitimate titles

The validation provides helpful, specific error messages for each failure case, guiding users to create better titles.

Fixes github#3.

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[JaclynCodes]

Nice

[JaclynCodes]

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[JaclynCodes]

Ok