- limit the showcase catalog to 21.1.2, 20.1.2, and 19.1.2
- add SDCoreJS favicon, author branding, and social metadata
- generate indexable route shells for GitHub Pages deep links

Verification: npm run test:showcase-generators; npm run test:showcase-branding; npm run check:sync; npm run lint:phase:release; npm --prefix versions/v19 run test:showcase; production showcase build

Replace the vendored datetime picker with the shared package integration,
add wrapper regression coverage, and preserve the approved handoff artifacts.

Verification: deferred by user
Blocked until @sdcorejs/angular-material-datetime@1.0.3 publishes a valid Angular Package Format entrypoint.

- pin the shared datetime picker runtime dependency across Angular 19-21
- remove the remaining vendored picker sources from derived workspaces
- seed committed picker state before open and cover model refresh regressions
- add integration, maintenance, and user documentation

Verification:
- focused datetime tests: 66/66 on v19, v20, and v21
- production library builds: pass on v19, v20, and v21
- sync, exact metadata, vendored-source, and staged hygiene checks: pass

Known gaps:
- full suites share 18 failures outside the datetime diff and miss global coverage thresholds
- Angular 20 deep npm ls reports an existing peer-minor mismatch
- browser visual/click smoke is deferred because no browser is available
- full release lint has 27 issues in files outside this commit; scoped datetime lint passes

Document the approved compact density contract for table settings.
Include editable desktop/mobile wireframes, switch states, and PNG previews.
Keep production implementation and temporary visual-companion files out of scope.

Document the approved repository-wide removal contract across Core UI,
Showcase, historical feature records, and published-doc archives.
Record the breaking no-stub decision and structural verification gates.
No production source changes are included.

Remove the AuthOM secondary entrypoint, Showcase references, historical records, and published documentation across Angular 19, 20, and 21.

Preserve supported auth, keycloak, permission, layout, and icon entrypoints while resolving the release lint baseline.

BREAKING CHANGE: @sdcorejs/angular/modules/authom has been removed with no compatibility stub.

Document the single-visible-placeholder model for palette, field, and row drag flows.

Record root-cause evidence, cleanup rules, regression coverage, and v19-first rollout constraints before implementation.

- add clearable=false inputs to text, number, color, date, and datetime controls
- enable clear actions for inline column and external table filters
- sync Angular 20/21 mirrors and document the public contract

Verification: v19 build; 333 focused tests; npm run lint:release; npm run check:sync; git diff --check
Known baseline: the full v19 suite has 17 unrelated failures outside this feature scope.