Hositrad - Per-Column Table Filter (Numeric Min + Material/Flange/Pins Dropdown + Combo + In Stock Toggle + Persistent Filters)

Adds per-column filter inputs above the product table on Hositrad product pages. Volt., AMPS, Bar and PSIG columns filter by minimum value (shows results >= entered value). In the Volt column, kV values are automatically converted to V (1 kV = 1000 V) before comparison. Numeric input fields (Volt., AMPS, etc.) have spinner arrows removed and are wide enough for 5-digit numbers. Material, Flange and Pins columns use a dropdown populated with unique values. Flange dropdown options are sorted numerically (smallest to largest), displayed without the NW prefix, with CF moved to the front (e.g. CF16, CF25) and KF moved to the front (e.g. KF16, KF25). Price ex., Qty and Code columns are excluded from search. Columns with only one unique value are not searchable. If the table has only one article, the search UI is hidden entirely. All other unnamed columns (e.g. D, D2, L) use a single combined input with a custom scrollable dropdown that always appears when typing or clicking, styled to match the other dropdown menus. A toggle button lets you show only in-stock items. Filter state is remembered per product type: navigating to a product and back restores the active filters; switching to a different product type clears them.