feat(#207): retire legacy coverage-bucket test files

 Move the pre-migration broad coverage-bucket suites (CoverageGaps*,
 CoverageCompletion*, Remaining*Coverage*, broad NovaCommandModel*) and
 their legacy-only support sidecars to tests/_legacy/ and rename the
 .Tests.ps1 suffix to .LegacyReference.ps1 so Pester discovery no longer
 runs them. The mirrored tests/public/ and tests/private/<domain>/
 suites added in #200 – #206 now own that coverage. The retired files
 stay readable as a reference until coverage measurement is re-enabled
 and confirms no regression. Active tests that still consume
 RemainingHelperCoverage.TestSupport.ps1 and CoverageGaps.Cli.TestSupport.ps1
 keep their existing support files in place.

Author: stiwicourage

CHANGELOG.md

@@ -31,6 +31,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 
 ### Changed
+- Retired the pre-migration broad coverage-bucket suites (`CoverageGaps*`, `CoverageCompletion*`, `Remaining*Coverage*`, broad `NovaCommandModel*`) by moving them to `tests/_legacy/` and renaming the `.Tests.ps1` suffix to `.LegacyReference.ps1` so Pester discovery no longer runs them. The mirrored `tests/public/` and `tests/private/<domain>/` suites added in #200 – #206 now own that coverage; the retired files stay readable as a reference until coverage measurement is re-enabled and confirms no regression. Active tests that still consume `RemainingHelperCoverage.TestSupport.ps1` (`PackageLatestPolicy.Tests.ps1`) and `CoverageGaps.Cli.TestSupport.ps1` (`CliHelperCoverage.Tests.ps1`, `CliSharedParser.Tests.ps1`) keep their existing support files in place.
 - Test-loading guidance for NovaModuleTools' own tests and for generated Agentic Copilot scaffolds now follows a source-mirrored, dot-source-first pattern: new mirrored tests dot-source the relevant `src/**/*.ps1` files directly in `BeforeAll` instead of importing the built `dist` module or wrapping assertions in `InModuleScope`, so tests run against source files and JaCoCo coverage references real source paths.
 - `project.json` `Pester.CodeCoverage.Enabled` is temporarily `false` while the existing test suite migrates to the new dot-source pattern; the configured `90` percent target stays in place and is re-enabled once migration completes.
 - The architect/design flow now surfaces settled vs unresolved design items before finalization, offers explicit choices for full finalization vs design-package-only handoff, clarifies how to use design notes versus the paste-ready GitHub issue draft, and requires finalization output to follow the project Markdown authoring guidance.

tests/_legacy/README.md

@@ -0,0 +1,21 @@
+# `tests/_legacy/` — retired coverage-bucket suites
+
+These files were the broad pre-migration coverage buckets (`CoverageGaps*`,
+`CoverageCompletion*`, `Remaining*Coverage*`, broad `NovaCommandModel*`)
+that existed before each `src/**/*.ps1` helper got its own mirrored test
+file under `tests/public/` and `tests/private/<domain>/`.
+
+After the source-mirrored test migration (issues #200 – #206), their
+assertions are covered by the mirrored tests. They are kept here, with
+the `.Tests.ps1` suffix renamed to `.LegacyReference.ps1`, so:
+
+- Pester discovery (which only picks up `*.Tests.ps1`) skips them and they
+  no longer run as part of `Test-NovaBuild` or the repository quality
+  loop.
+- If a behavior is later found to be missing from the mirrored suites,
+  the original assertion is still readable here as a reference and can
+  be ported to the right mirrored or cross-cutting test home.
+
+These files are not maintained. They will be deleted once coverage
+measurement is re-enabled and confirms no regression against the
+mirrored test layout.