Implement mobile view

[marcelveldt]

Currently only a desktop view has been implemented and only some very rough initial mobile layout.

[jesserockz]

Multiple select footer bar is broken on mobile - too wide

[jesserockz]

New device dialog shows two columns of "other boards", should be one single column

[swoboda1337]

The table view (esphome-device-table) doesn't fit on mobile viewports. Currently 7 columns are default-visible (select, status, name, address, platform, config, actions) and the only responsive behaviour at narrow widths is a horizontal scroll bar on .table-scroll. Phones get a tiny, scroll-only view of a table designed for desktop widths.