feat: add GitHub notifications tools for managing user notifications

[sridharavinash]

GitHub Notifications Tooling

This PR adds support for managing GitHub notifications

Features Added

New Tools

• get_notifications: Retrieve a list of notifications for the authenticated GitHub user with filtering options for read/unread status, participation, and time ranges
• mark_notification_read: Mark a specific notification thread as read
• mark_notification_done: Mark a specific notification thread as done
• mark_all_notifications_read: Mark all notifications as read with an optional timestamp
• get_notification_thread: Fetch details of a specific notification thread

Technical Implementation

• Implements proper error handling and status code validation
• Provides RFC3339/ISO8601 timestamp parsing for time-related parameters
• Integrates with the existing GitHub API client infrastructure
• Respects read-only mode settings for mutating operations

[Copilot]

Pull Request Overview

This PR introduces new GitHub notifications management tooling to allow users to retrieve notifications, mark them as read (individually or in bulk), and fetch detailed thread information.

• Added notifications tools to the server initialization in pkg/github/server.go.
• Implemented functions in pkg/github/notifications.go for handling notification retrieval and state updates with appropriate error handling and time parsing.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
pkg/github/server.go	Added notifications tools and helper functions for optional params.
pkg/github/notifications.go	Implements API integrations for GitHub notifications management.

Comments suppressed due to low confidence (2)

pkg/github/server.go:262

• The condition unconditionally returns the default value when v is false, which means an explicit false value from the user is ignored. Consider checking for the presence of the parameter instead of evaluating its boolean value directly.

if !v { return d, nil }

pkg/github/notifications.go:130

• [nitpick] The parameter name 'getclient' is inconsistent with other functions that use 'getClient'. Consider renaming it to 'getClient' for consistency.

func MarkNotificationRead(getclient GetClientFn, t translations.TranslationHelperFunc) (tool mcp.Tool, handler server.ToolHandlerFunc) {