fix: show+hide architecture update

[thiessenp-cds]

Summary | Résumé

This PR moves show+hide to use an event-driven approach that is more performant and maintainable. It separates concerns cleanly and makes the visibility logic testable in isolation. (though UI test would also help -- potential followup PR)

Summary of how the new implementation works:

1. On form mount, dependency graph (dependent elements) is built showing which elements depend on which
2. Initial visibility is computed for all elements and cached in a Map
3. When form values change:
   • System detects which choice-based elements (radio/checkbox/select) changed
   • Filters to only those with dependents (using dependency graph)
   • Recomputes visibility only for affected elements
   • Fires custom event for extensibility
4. Components simply check the cached visibility map (fast lookup)

Additionally visibilityMap has been moved out of GCFormsContext into its own dedicated VisibilityContext. This scopes re-renders from visibility changes to only components that consume useVisibilityContext. Previously, any change to visibilityMap would trigger a re-render in every component subscribed to useGCFormsContext.

Note:
A follow up PR is needed to add (back?) accessibility semantics (aria-controls + aria-expanded) for show+hide. These semantics are just WCAG related they don't actually do much to help screen reader users. An announcement should also be used, or a similar strategy.

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[Copilot]

Pull request overview

This PR refactors show/hide visibility evaluation to a more incremental, event-driven approach: it precomputes element dependency relationships, caches visibility results, and updates only impacted elements when relevant form values change. It also introduces a custom event (form-values-changed) so UI components can update visibility without re-running full visibility checks.

Changes:

• Added dependency-graph + cached visibility computation APIs in @gcforms/core (compute-all + recompute-affected).
• Updated the form context and ConditionalWrapper to use cached visibility and a custom event to propagate visibility changes.
• Added Vitest coverage for the new visibility helper functions and bumped core version + changelog.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
packages/core/src/visibility.ts	Adds dependency graph + cached visibility map computation and incremental recomputation helpers.
packages/core/src/index.ts	Re-exports the new visibility APIs/types from core.
packages/core/package.json	Bumps @gcforms/core version to 2.2.15.
packages/core/CHANGELOG.md	Documents the visibility refactor in the changelog.
lib/vitests/visibility.test.ts	Adds unit tests covering new visibility helper behavior.
lib/hooks/useGCFormContext.tsx	Computes and maintains a visibility map and fires an event describing visibility diffs on value changes.
lib/hooks/useCustomEvent.tsx	Adds form-values-changed key and fixes event listener removal behavior.
components/clientComponents/forms/ConditionalWrapper/ConditionalWrapper.tsx	Switches to event-driven local visibility updates via the cached visibility map.

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[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 5 comments.