X1C and X1 virtual printers used legacy SSDP model codes
(3DPrinter-X1-Carbon, 3DPrinter-X1) that BambuStudio doesn't
recognize, causing "incompatible printer preset" errors when
sending prints. Changed to the correct codes (BL-P001, BL-P002)
that real printers report via SSDP.
Also fixed proxy mode auto-inherit storing printer display names
(e.g. "X1C") instead of SSDP codes, by adding a resolution layer
that maps display names to model codes.
DB migration auto-converts existing VPs on startup.
Virtual printers in Queue mode now have an "Auto-dispatch" setting.
When enabled (default), prints start automatically — preserving current
behavior. When disabled, prints are added with manual_start so they
wait for manual dispatch from the queue UI.
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