Refactored Activities for clarity and a consistent API

[austincondiff]

Description

This PR refactors the Activity Manager to provide a more Swift-like, type-safe API similar to our NotificationManager. It removes the dependency on NotificationCenter and provides a cleaner interface for managing activities within workspaces. This refactor aligns with CodeEdit’s architecture by ensuring activities are workspace-specific while keeping notifications global.

Note

To test this, go to Settings, press F12, toggle on "Show Internal Development Inspector". In a workspace, go to the Internal Development Inspector in the Inspector Area, and then test Activities using the Activities form.

Changes

Filesystem changes

CodeEdit/
└── CodeEdit/
│   └── Features/
│       └── Activities/                               (previously ActivityViewer)
│           ├── ActivityManager.swift                 (previously TaskNotificationHandler)
│           ├── Models/
│           │   └── CEActivity.swift                  (previously TaskNotificationModel)
│           └── Views/
│                ├── ActivityView.swift               (previously TaskNotificationView) 
│                └── ActivitiesDetailView.swift       (previously TaskNotificationsDetailView)
└── CodeEditTests/
    └── Features/
        └── Activities/                               (previously ActivityViewer)
            └── ActivityManagerTests.swift            (previously TaskNotificationHandlerTests)

New API

Activities can now be created, updated and deleted using a simple, fluent API:

@ObservedObject var activityManager: ActivityManager

// Create
let activity = activityManager.post(
    title: "Indexing Files",
    message: "Processing workspace files",
    isLoading: true
)

// Create with priority (shows at top of list)
let activity = activityManager.post(
    priority: true,
    title: "Building Project",
    message: "Compiling sources",
    percentage: 0.0,
    isLoading: true
)

// Update
activityManager.update(
    id: activity.id,
    percentage: 0.5,
    message: "50% complete"
)

// Delete
activityManager.delete(id: activity.id)

// Delete with delay
activityManager.delete(id: activity.id, delay: 4.0)

Architecture Changes

• Activities are now scoped to workspaces instead of being global
• ActivityManager is now a proper ObservableObject
• Removed NotificationCenter-based activity management
• Added proper type safety for activity parameters
• Activities are now properly tracked and referenced by their own IDs

Migration

Updated existing activity creators to use new API:

• Task execution activities in CEActiveTask
• File indexing activities in WorkspaceDocument+Index
• Updated tests to verify new API behavior

Checklist

• I read and understood the contributing guide as well as the code of conduct
• The issues this PR addresses are related to each other
• My changes generate no new warnings
• My code builds and runs on my machine
• My changes are all related to the related issue above
• I documented my code