Add FilterSelect: include/exclude combobox on the shared shell

FilterSelect renders value rows with +/- (include/exclude) buttons, check/cross
pills for the included/excluded sets, and an optional set of pinned modifier
pseudo-options (e.g. (Any)/(None)) that stay visible above the value rows. A
selected modifier is mutually exclusive with value pills. It delegates assembly
to _combobox_shell and supports both pre-rendered options (complete set) and
search_url + prefetch (windowed); included/excluded are passed as resolved
value+label so pills show labels even outside the fetched window. Styling is
inline (ported from the old SelectableFilter CSS) so nothing lives in input.css.

https://claude.ai/code/session_01XzhXvMvw42CQGc9kmin3GS

common/components/__init__.py

@@ -40,6 +40,7 @@ from common.components.primitives import (
     paginated_table_content,
 )
 from common.components.search_select import (
+    FilterSelect,
     SearchSelect,
     SearchSelectOption,
     searchselect_selected,
@@ -85,6 +86,7 @@ __all__ = [
     "Popover",
     "PopoverTruncated",
     "SearchField",
+    "FilterSelect",
     "SearchSelect",
     "SearchSelectOption",
     "searchselect_selected",