feat: Add createDraftNote api support, useful for bulk code review

[g-tiwari]

Overview

This PR adds complete support for GitLab's Draft Notes API, enabling users to create, manage, and publish draft comments on merge requests
before making them visible to other collaborators.

What are Draft Notes?

Draft Notes are a GitLab feature that allows users to:
• Write comments on merge requests that are only visible to the author
• Review and edit comments before publishing
• Publish individual draft notes or all drafts at once
• Add comments to specific lines in diffs (with position support)

Features Added

🛠️ New Tools (6 total)

1. list_draft_notes - List all draft notes for a merge request
2. create_draft_note - Create a new draft note with optional diff positioning
3. update_draft_note - Update existing draft note content or position
4. delete_draft_note - Delete a draft note
5. publish_draft_note - Publish a single draft note to make it visible
6. bulk_publish_draft_notes - Publish all draft notes for a merge request at once

🔧 Technical Improvements

• Flexible Schema Validation: Enhanced schemas to handle GitLab API inconsistencies
• Position Support: Full support for diff positioning in draft comments
• Error Handling: Robust handling of empty responses from GitLab API
• Parameter Normalization: Handles both body and note field variations
• Type Safety: Complete TypeScript definitions for all draft note operations

Implementation Details

Core Functions (index.ts)

• Added 6 new API functions with comprehensive error handling
• Implemented proper URL encoding and parameter validation
• Added support for diff positioning and discussion resolution
• Enhanced response parsing to handle GitLab's variable response formats

Schema Definitions (schemas.ts)

• Created flexible GitLabDraftNoteSchema with field normalization
• Added separate schemas for each operation (CRUD + publish operations)
• Split position schemas into flexible (responses) and strict (creation) variants
• Made user schema fields optional for better API compatibility

Documentation Updates

• Updated README.md with new tool descriptions
• Added comprehensive inline documentation for all functions
• Included parameter descriptions and usage examples

API Endpoints Covered

GET /projects/:id/merge_requests/:merge_request_iid/draft_notes
POST /projects/:id/merge_requests/:merge_request_iid/draft_notes
PUT /projects/:id/merge_requests/:merge_request_iid/draft_notes/:draft_note_id
DELETE /projects/:id/merge_requests/:merge_request_iid/draft_notes/:draft_note_id
PUT /projects/:id/merge_requests/:merge_request_iid/draft_notes/:draft_note_id/publish
POST /projects/:id/merge_requests/:merge_request_iid/draft_notes/bulk_publish

Breaking Changes

None - this is a purely additive feature that doesn't modify existing functionality.

Usage Example

typescript
// Create a draft note
await createDraftNote("project-id", "123", "This needs improvement", {
position_type: "text",
base_sha: "abc123",
head_sha: "def456",
start_sha: "ghi789",
new_path: "src/file.js",
new_line: 42
});

// Publish all drafts when ready
await bulkPublishDraftNotes("project-id", "123");

Benefits

• Improved Code Review Workflow: Users can draft and refine comments before publishing
• Better Collaboration: Reduces noise in merge request discussions
• Enhanced Productivity: Bulk operations save time when reviewing large changes
• Complete API Coverage: Full parity with GitLab's native draft notes functionality

[g-tiwari]

thanks for creating this MCP.
@zereight @iwakitakuma33 Can you guys review this pull request for draft_note API. ?

[iwakitakuma33]

@g-tiwari thanks!!

related #197