[FE-30] Build Workspace Search and Filter Panel with debounced search

[devwums]

Problem

The workspace list page shows all workspaces with no search or filtering. At scale, users cannot discover relevant spaces without scrolling through an unfiltered list.

Proposed Solution

Create frontend/cntr/WorkspaceFilter/WorkspaceFilterPanel.tsx. Props: onFilterChange: (filters: WorkspaceFilters) => void. WorkspaceFilters = { search: string, minCapacity?: number, maxPriceKobo?: number, amenities: string[] }. Renders: a debounced (300ms) text search input, a capacity number input, a max price input (displayed in ₦), and amenity checkboxes for at least 6 options. "Clear all" button resets all filters. All implementation must live inside frontend/cntr/.

Acceptance Criteria

• File at frontend/cntr/WorkspaceFilter/WorkspaceFilterPanel.tsx
• Text search is debounced by 300ms before calling onFilterChange
• Price input displayed in ₦ but submitted in kobo (multiply by 100)
• At least 6 amenity checkboxes with predefined labels
• "Clear all" resets all inputs to their default empty state
• Test in frontend/cntr/WorkspaceFilter/WorkspaceFilterPanel.test.tsx