Pins: Add sidebar for pinned map cards

[RutanshS]

Fixes #669

Summary: Replaces the floating map cards with a sidebar panel. Pinned entities appear in a scrollable sidebar on the left side of the map. Hovering on the said cards highlights the corresponding map centroids or territories.

Changes

• User experience
  • Clicking a map centroid or territory pins/unpins it. (Toggle)
  • Pinned entities appear in a sidebar panel instead of floating over the map.
  • Hovering a sidebar card highlights the corresponding centroid or territory on the map.
  • Clicking anywhere else on the map no longer closes all cards.
• Logical changes
  • EntityMap: Replaced FloatingCard state and map positioning logic with the MapSidebar Component and uses the pinnedEntities derived from the URL.
  • MapCentroids / MapTerritories: Added hoveredId and pinnedIds for visual feedback on pinned entities. Fixed pinCard typing.
• Refactors
  • Renamed openCard to pinCard and closeCard to unpinCard to match the actual behavior.
  • Removed the mapScale, updateMapScale and handleZoomIn function wrappers that existed only for positioning floating cards.

Out of scope/Future work: Unit Tests, Clear All Button in sidebar, Maximum Pin Limit (Maybe).

Screenshots

Pinned Single Card

Pinned Multiple Cards

Pinned Card Hover

[github-actions]

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• Deploy URL: https://ed1c0434.lang-nav.pages.dev/lang-nav/
• Branch alias: https://pr-683.lang-nav.pages.dev/lang-nav/
  Commit: 73050a2