feat: implement pinned friends functionality in ConnectViewModel and UI

[JothishKamal]

Pull Request Type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build related changes
• Documentation content changes
• Other (please describe):

Purpose

• WHAT is this PR for?
  This PR introduces a "pinned friends" feature on the Connect screen, enabling users to pin up to three friends for easier access.

Approach

• HOW does this change fulfill the purpose?
  • Added pinnedFriends state in ConnectViewModel backed by SharedPreferences.
  • Methods implemented to pin, unpin, check pin status, and initialize pinned friends.
  • UI updated to show pinned friends at the top of the list, maintaining their order.
  • FriendCard component updated with a pin/unpin icon, with a toast shown when exceeding the pin limit.
  • State management and imports added across components to support the feature.

Does this PR introduce any new bug?

• Yes
• No
• Maybe

Issue Reference: (No issue link provided)

Other information

• Toast feedback is included when a user attempts to pin more than 3 friends.
• The feature ensures pinned friends are displayed consistently across app sessions using persistent storage.

Did you learn something new?

• Learned to integrate UI state with persistent storage using SharedPreferences.
• Implemented logic to handle limited-size pinned lists with feedback in UI.

[dk-a-dev]

Attach screen shot of ui

[JothishKamal]

Attach screen shot of ui