feat(gui): enable Hybrid nozzle flow for multi-sub-nozzle extruders

An extruder with more than one physical sub-nozzle can hold a mix of
Standard and High Flow nozzles. The Flow dropdown now offers Hybrid for
such extruders (extruder_max_nozzle_count > 1, nil-guarded); grouping
already expands a Hybrid extruder into per-volume nozzle groups from
extruder_nozzle_stats.

- sidebar Flow combo offers Hybrid only for multi-sub-nozzle extruders
- preset lookup treats Hybrid as Standard (presets define no Hybrid
  variant); variant strings are never fabricated for it
- printer tab splits a Hybrid extruder into Standard + High Flow rows,
  with matching selection-index arithmetic and sync-enable rules
- syncing from a printer whose extruder holds mixed nozzle flows now
  selects Hybrid instead of collapsing to the dominant flow type
- send-to-printer flow check: a nozzle-rack extruder validates its
  nozzle inventory (mounted + rack) against every needed flow instead
  of comparing only the mounted nozzle; mounted-flow lookup is now
  per-extruder, fixing an index shift when a nozzle reports no flow
- Hybrid is session-only in app config (stored as Standard), so a
  fresh session starts from concrete flow types

Printers whose extruders have a single sub-nozzle (including all
dual-extruder machines without a rack) see no new option and identical
check behavior.

localization/i18n/OrcaSlicer.pot

@@ -18749,3 +18749,9 @@ msgstr ""
 
 msgid "Both"
 msgstr ""
+
+msgid ""
+"The printer has no nozzle matching the slicing file (%s). Please install a "
+"matching nozzle on the printer, or set the corresponding printer preset "
+"while slicing."
+msgstr ""