feat(datagrid): redesign filter panel header and row actions

[J2TeamNNL]

Changes

Implements the new filter panel interaction model:

Clear vs Remove All

• "Unset" renamed to "Clear": calls clearAppliedFilters() — keeps all filter rows, just removes the applied state so the table returns to unfiltered results.
• New "Remove All Filters" item added to the ... options menu: calls clearFilterState() — removes all filter rows entirely.

Per-row Apply moved to context menu

• Per-row Apply / Applied buttons removed from the inline row layout.
• "Apply Only This Filter" added to each row's right-click context menu (calls the existing applySoloFilter path).

Tri-state toggle-all checkbox

• SF Symbols button (checkmark.square.fill / square / minus.square.fill) added to the filter panel header.
• Shows checked when all rows are enabled, unchecked when none are, dash when mixed.
• Clicking toggles all rows to enabled (if any are off) or all to disabled (if all are on).

Files: TablePro/Views/Filter/FilterPanelView.swift, TablePro/Views/Filter/FilterRowView.swift

Test plan

• Click "Clear" — filter rows stay, table reloads without filters; button is disabled when no filters applied
• ... menu > "Remove All Filters" — all rows removed, table reloads unfiltered
• Right-click a filter row > "Apply Only This Filter" — only that filter is applied
• With all rows enabled: tri-state shows checkmark; clicking disables all
• With no rows enabled: tri-state shows empty square; clicking enables all
• With mixed enabled state: tri-state shows dash; clicking enables all