🎯 Goal

Make the Vite example state bookmarkable and shareable by syncing the active channel, the selected main view, and the selected thread with the URL.

🛠 Implementation details

• Read a channel query param in the Vite example and pass it to ChannelList.customActiveChannel.
• Read a view query param and restore the selected main view on load, supporting view=chat and view=threads.
• Read a thread query param and restore the selected thread when the threads view mounts.
• Sync the active channel, the active view, and the active thread back into the URL with history.replaceState while preserving existing params like token and user_id.
• Prefer the thread object already present in the thread list so the restored thread also stays selected in the list UI.
• Fall back to the first channel when customActiveChannel is missing or invalid.
• Add coverage for the customActiveChannel fallback behavior.
• Add the shared matchMedia Jest polyfill and missing React imports needed for the exercised test path.

🎨 UI Changes

N/A. This changes URL state only.