profiles: fix belt printer CI failures (slice check + setting_id)

The belt-printer branch is failing two profile gates. Both stem from the
three belt-only vendors (Custom's generic belt printer, IdeaFormer,
Printcepts) not existing upstream, so upstream maintenance passed them by.

Slice check: 4 of 1015 printers failed - Custom's MyBeltPrinter 0.2/0.4/
0.6/0.8 nozzle all fell back to "Default Setting". No process profile in
the Custom vendor listed any MyBeltPrinter in compatible_printers, and
Custom's fdm_belt_common pointed default_print_profile at
"0.20mm Standard @System", which does not exist in that vendor's index,
so the generic belt printer had no usable process at all. This gap dates
to when MyBeltPrinter was added (2026-04-07); it only started failing now
because the slice-check job is newer than that.

Adds two process profiles modelled on the sibling @MyKlipper ones:
  - 0.20mm Standard @MyBeltPrinter - 0.4/0.6/0.8 nozzles
  - 0.12mm Fine @MyBeltPrinter     - 0.2/0.4 nozzles
The split is forced by hardware: the 0.2 nozzle preset caps
max_layer_height at 0.16, so a single 0.20mm profile cannot legally cover
it. fdm_belt_common now defaults to the standard profile and the 0.2
nozzle preset overrides to the fine one.

setting_id: 14 files failed the rules introduced in #14432. That
migration renumbered 7425 files across 61 vendors but skipped these three,
leaving BabyBelt Pro, IdeaFormer IR3 V2 and MyBeltPrinter squatting the
"G*" id space reserved for Bambu (GMPC0BBP01, GMIF001, GM_BELT_00x) and
four instantiated filament/process presets carrying no setting_id at all.
Regenerated with scripts/assign_vendor_setting_ids.py.

Also repoints the identical dangling "0.20mm Standard @System" in
Printcepts' and IdeaFormer's fdm_belt_common at their own real process
profiles. That is a no-op today because both concrete printers override
it, but it is the same landmine that took out MyBeltPrinter.

Vendor index versions bumped so check_installed_vendor_profiles() will
re-install the corrected profiles over an existing install.

Note: changing a shipped preset's setting_id can orphan user presets that
reference it as base_id. #14432 accepted that tradeoff for 61 vendors;
this keeps these three consistent with the rest.

Verified: orca_extra_profile_check.py reports 0 errors across 66 vendors
(was 14 files with errors), and OrcaSlicer_profile_validator -s slices all
1015 printer presets successfully (was 4 failures).

resources/profiles/Custom/machine/MyBeltPrinter 0.2 nozzle.json

@@ -3,9 +3,10 @@
 	"name": "MyBeltPrinter 0.2 nozzle",
 	"inherits": "fdm_belt_common",
 	"from": "system",
-	"setting_id": "GM_BELT_001",
+	"setting_id": "3w1uyJdmm14QhDnH",
 	"instantiation": "true",
 	"printer_model": "Generic Belt Printer",
+	"default_print_profile": "0.12mm Fine @MyBeltPrinter",
 	"nozzle_diameter": [
 		"0.2"
 	],

resources/profiles/Custom/machine/MyBeltPrinter 0.4 nozzle.json

@@ -3,7 +3,7 @@
 	"name": "MyBeltPrinter 0.4 nozzle",
 	"inherits": "fdm_belt_common",
 	"from": "system",
-	"setting_id": "GM_BELT_002",
+	"setting_id": "6nRHUtvJOUffocbu",
 	"instantiation": "true",
 	"printer_model": "Generic Belt Printer",
 	"nozzle_diameter": [

resources/profiles/Custom/machine/MyBeltPrinter 0.6 nozzle.json

@@ -3,7 +3,7 @@
 	"name": "MyBeltPrinter 0.6 nozzle",
 	"inherits": "fdm_belt_common",
 	"from": "system",
-	"setting_id": "GM_BELT_003",
+	"setting_id": "K0m9HbUNwKT4UCJV",
 	"instantiation": "true",
 	"printer_model": "Generic Belt Printer",
 	"nozzle_diameter": [

resources/profiles/Custom/machine/MyBeltPrinter 0.8 nozzle.json

@@ -3,7 +3,7 @@
 	"name": "MyBeltPrinter 0.8 nozzle",
 	"inherits": "fdm_belt_common",
 	"from": "system",
-	"setting_id": "GM_BELT_004",
+	"setting_id": "rHAweDz4eNwttPNA",
 	"instantiation": "true",
 	"printer_model": "Generic Belt Printer",
 	"nozzle_diameter": [

resources/profiles/Custom/machine/fdm_belt_common.json

@@ -9,7 +9,7 @@
 	"default_filament_profile": [
 		"Generic PLA @System"
 	],
-	"default_print_profile": "0.20mm Standard @System",
+	"default_print_profile": "0.20mm Standard @MyBeltPrinter",
 	"max_layer_height": [
 		"0.32"
 	],