issue 2630 residual: stop shipping product Widget def XML batch A (base/core) #2883

Parent

Parent: #2630
Grandparent: #2626
Related dual-ship modern roots: cluster PR #2862 (#2831/#2832/#2844)

Slice goal

Stop shipping product Widget definition XML for batch A (base/core) packages that already have modern widgets/<stem>/ dual-ship roots, so M1 (product packages free of Widget def XML as ship format) progresses without removing the customer-facing runtime shim.

In scope

1. Identify base/core product packages whose modern roots already landed (batch A set from dual-ship exit)
2. Remove or stop packaging sys__UserDependency--rxconfig/Widgets/*.xml for those packages only when modern component-package.json / widgets roots are present and compile/install tests cover them
3. Keep PSLegacyDefinitionXmlShim + upgrade compilers; do not implement Phase 5 residual: remove definition-XML dual-run shim when criteria met #2852 shim deletion
4. Unit/package tests green; update widget-xml inventory notes for this batch
5. cd modules/perc-packages && …/mvnw clean install green

Out of scope

• High-traffic / long-tail Widget XML ship exit (siblings)
• Runtime shim hard-delete (Phase 5 residual: remove definition-XML dual-run shim when criteria met #2852 — criteria not met)
• Mass customer XML conversion
• Page/Gadget ship-format work unless forced by shared packaging helpers

Acceptance

• Measurable reduction in product Widget def XML count for batch A packages (document before/after)
• Modern-only path still compiles/installs for those packages
• No product behavior change for modern authoring; legacy customer XML still loadable via shim
• Update parent [8.2] Template/assembler Phase 3: eliminate product definition XML packaging #2630 / [8.2] Template & assembler model normalization (epic) #2626 Agent progress

Modules

modules/perc-packages (primary); packaging/distribution only if install peers require it

Leave unassigned.

Refs #2630 #2626 #2862