ENH: Migrate ctkDICOMModalities to ctkDICOMDatabase accessors (stacked on #1418)

[hjmjohnson]

Migrates the ctkDICOMModalities namespace from a header-only definition to deprecated free functions, with the supported-modality lists moved onto ctkDICOMDatabase as the new home. Stacked on #1418 (the CTK_DEPRECATED_SINCE framework).

This PR was previously the four-commit "framework + migration" series. The framework commit has been split out to #1418 to make review easier; this PR now contains only the three migration commits and will rebase to a clean series once #1418 merges.

What this PR changes

1. ENH: Add modality list accessors to ctkDICOMDatabase — adds supportedModalities(), defaultModalities(), and modalitiesExcludedFromThumbnailGeneration() as the new authoritative home for the lists, per @lassoan's review on the original draft of ENH: Migrate ctkDICOMModalities to ctkDICOMDatabase accessors (stacked on #1418) #1411 (comment).
2. ENH: Migrate DICOM modality call sites to ctkDICOMDatabase accessors — switches every in-tree caller to the new ctkDICOMDatabase accessors.
3. ENH: Deprecate ctkDICOMModalities namespace and move definitions out-of-line — wraps the legacy free functions in #if CTK_DEPRECATED_SINCE(0, 1) and moves their bodies to a .cpp so they no longer pollute the header. External consumers continue to compile until they raise CTK_DISABLE_DEPRECATED_BEFORE.

Stacking / merge order

PR	Scope	Status
#1418	CTK_DEPRECATED_SINCE framework only	depends on nothing; merge first
this PR (#1411)	ctkDICOMModalities → ctkDICOMDatabase migration	depends on #1418

Both PRs target master. While #1418 is open, the framework commit appears in both PRs' commit lists; once #1418 merges, GitHub will rebase this branch and only the three migration commits will remain.

[lassoan]

Having a clear deprecation framework for Qt classes would be nice.

I would choose a different solution for the new implementation of the deprecated methods, as ctkDICOMModalities should be completely phased out in the long term:

• AllModalities and CommonImagingModalities: the contents of these lists are application-dependent. There should be a way developers can change this list. They should be methods in ctkDICOMDatabase because that is already a place where application-specific behavior can be configured by registering ctkDICOMDisplayedFieldGenerator rules and various other settings. -> We should replace ctkDICOMModalities::AllModalities and ctkDICOMModalities::CommonImagingModalities by ctkDICOMDatabase::supportedModalities and ctkDICOMDatabase::defaultModalities.
• ExcludedFromThumbnailGeneration: only the thumbnail generators know what modalities they can process, so it does not make sense to statically hardcode the values in another class. -> We should replace ctkDICOMModalities::excludedFromThumbnailGeneration by ctkDICOMDatabase::modalitiesExcludedFromThumbnailGeneration.

[hjmjohnson]

@lassoan thanks for the review. I've split this PR into two phases per your feedback:

This PR (Phase A) is now framework-only: it just adds the CTK_DEPRECATED_SINCE macro infrastructure (in a new standalone Libs/ctkDeprecated.h, not in ctkExport.h.in). No CTK API is migrated.

Follow-up PR (Phase B) will migrate ctkDICOMModalities per your design — ctkDICOMDatabase::supportedModalities / defaultModalities / modalitiesExcludedFromThumbnailGeneration as the new home, with the existing ctkDICOMModalities::* static lists kept behind CTK_DEPRECATED_SINCE(0,1) for source compatibility during the transition.

Before I write Phase B, one design question on the migration: several internal call sites that read these lists today (e.g. ctkDICOMSeriesModel, ctkDICOMPatientModel, ctkDICOMStudyModel) don't currently hold a ctkDICOMDatabase*. Options for those callers:

1. Add a setDatabase(ctkDICOMDatabase*) to each model and require it be set before use.
2. Keep a fallback to the static defaults when no database is attached.
3. Something else you'd prefer.

Happy to follow whichever pattern matches the existing conventions in ctkDICOMDatabase callers.

[hjmjohnson]

@lassoan I went ahead with option 2 — fall back to the static defaults when no database is attached — as I think that's the correct choice here. It preserves existing behavior 1:1 (the model classes initialize their ModalityFilter member at construction, before any setDicomDatabase() call, and the database is seeded with the historical static defaults anyway), while letting applications override the lists per ctkDICOMDatabase once one is attached.

Phase B is now pushed as three commits on top of the framework commit:

Commit	What
2dc4c7e0c	Add supportedModalities() / defaultModalities() / modalitiesExcludedFromThumbnailGeneration() accessors (with setters, change-notification signals, and Q_PROPERTY bindings) to ctkDICOMDatabase, seeded from the existing static defaults.
fd2b206c3	Migrate the five internal call sites (ctkDICOMSeriesModel, ctkDICOMPatientModel, ctkDICOMStudyModel, ctkDICOMScheduler, ctkDICOMVisualBrowserWidget) to query the database first and fall back to ctkDICOMModalities::* only when no DB is attached.
148c9e2c7	Mark ctkDICOMModalities::AllModalities / ExcludedFromThumbnailGeneration / CommonImagingModalities as deprecated since CTK 0.1, move the data into Meyers' singletons in a new ctkDICOMModalities.cpp, and replace the in-header definitions with extern const QStringList&. Source compatibility is preserved; clazy's non-pod-global-static warning is gone (one shared copy across the whole library instead of one per TU).

Local Qt5 build of CTKDICOMCore and CTKDICOMWidgets is clean.

I'll let CI run and address any platform-specific issues. Ready for another look whenever you have time.