Docx reader: key list numbering off abstractNumId.

Word represents "restart numbering" on a style-based list by pointing
only the first item of the restarted list at a new `numId` that shares the
original list's abstract numbering definition but carries a
`w:startOverride`; the remaining items keep using the original `numId`.

Pandoc keyed list continuation and grouping on the `numId`, so the
restarted items continued the stale count from the earlier list (and
were split into a separate ordered list with the wrong start).

Key continuation and grouping off the `abstractNumId` instead (the real
running counter in Word), and treat `startOverride` as a restart that
resets the count.

Closes #8367.

Co-Authored-By: Claude <noreply@anthropic.com>

test/Tests/Readers/Docx.hs

@@ -281,6 +281,10 @@ tests = [ testGroup "document"
             "sublists reset numbering to 1"
             "docx/lists_sublist_reset.docx"
             "docx/lists_sublist_reset.native"
+          , testCompare
+            "style-based list restarted on one item (#8367)"
+            "docx/lists_restart_8367.docx"
+            "docx/lists_restart_8367.native"
           , testCompare
             "definition lists"
             "docx/definition_list.docx"

test/docx/lists_restart_8367.native

@@ -0,0 +1,13 @@
+[Header 1 ("section-1",[],[]) [Str "Section",Space,Str "1"]
+,OrderedList (1,Decimal,Period)
+ [[Para [Str "Item",Space,Str "1"]]
+ ,[Para [Str "Item",Space,Str "2"]]
+ ,[Para [Str "Item",Space,Str "3"]]]
+,Para [Str "Conclusion"]
+,Header 1 ("section-2",[],[]) [Str "Section",Space,Str "2"]
+,OrderedList (1,Decimal,Period)
+ [[Para [Str "Item",Space,Str "1"]]
+ ,[Para [Str "Item",Space,Str "2"]]
+ ,[Para [Str "Item",Space,Str "3"]]
+ ,[Para [Str "Item",Space,Str "4"]]]
+,Para [Str "Conclusion"]]