4. Custom Filter State Management

[MitchellShiell]

Context
The existing DictionaryStateContext manages a single FilterOptions filter (Required / All Fields). Custom meta filters need their own dedicated state that can hold multiple selected values across multiple categories simultaneously.

Goal
Extend DictionaryStateContext to hold and manage the state for custom meta filters, which values are selected for each filter category, and expose actions to update and reset them.

Acceptance Criteria

• State is keyed per configured filterProperty, holding an array of selected values
• Individual values can be toggled (select / deselect)
• An action is available to reset all custom filter selections at once
• The existing FilterOptions state is unaffected
• State resets when the selected dictionary version changes