feat: render raster logos, add paper width, fix serial reception

[STT196]

Summary

Adds full ESC/POS raster-image (logo) support to the receipt printer emulator, plus a paper-width setting and a serial-reception bugfix.

Changes

• GS v 0 bit-image parsing: decodes the raster and renders the logo inline in the receipt preview as a real bitmap, proportional to the paper width.
• Paper width: new 58mm/80mm selector (saved per profile) that adjusts text columns and image scale.
• Serial fix: the serial listener used the default 4096-byte SerialPort buffer, dropping data on receipts larger than 4KB (images). Switched to a 256KB buffer and a continuous read loop.
• Command handling: added ESC d (feed) and GS V m n (cut) so they no longer emit "Unhandled byte" warnings.
• Log UX: added copy-to-clipboard buttons for the raw and parsed log panels.

Testing

• Verified against a POS emitting GS v 0 (384-wide logos) over both TCP and serial.
• dotnet build passes with 0 errors.