Add support for displaying local remote-control URLs and QR code in the
Settings UI, including styles for URL list, row layout, monospaced links,
and a QR container. Expose a new global API signature getLocalIpAddresses
for retrieving local IPs.
Fix several UI issues:
- Correct typo in header method name (opedAddPlaylistDialog -> openAddPlaylistDialog).
- Fix malformed GitHub URL and collapse img tag formatting.
- Reformat imports and viewChild usage for readability.
Change local development backend URL to localhost:3000 in the local
environment to point to the running local API during development.
These changes improve developer ergonomics (local backend), add a remote
control discovery UX for users on the same network, and tidy up header
bugs and formatting.
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