content: Markdown table import + 5 tests (round-trip, 460/460)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/content/tests/md-import.sx

@@ -4,6 +4,7 @@
 (st-bootstrap-classes!)
 (content/bootstrap!)
 (content-bootstrap-markdown!)
+(content-bootstrap-table!)
 
 (define nl (str "\n"))
 
@@ -81,6 +82,54 @@
   (doc-ids (md/import (str nl nl) "d"))
   (list))
 
+;; ── pipe tables ──
+(define
+  dt
+  (md/import
+    (str
+      "| Name | Age |"
+      nl
+      "| --- | --- |"
+      nl
+      "| Ada | 36 |"
+      nl
+      "| Al | 40 |")
+    "d"))
+(content-test "table import type" (doc-types dt) (list "table"))
+(content-test
+  "table headers"
+  (table-headers (doc-find dt "b0"))
+  (list "Name" "Age"))
+(content-test
+  "table rows"
+  (table-rows (doc-find dt "b0"))
+  (list (list "Ada" "36") (list "Al" "40")))
+(content-test
+  "table round-trip"
+  (asMarkdown
+    (md/import (str "| A | B |" nl "| --- | --- |" nl "| 1 | 2 |") "d"))
+  (str "| A | B |" nl "| --- | --- |" nl "| 1 | 2 |"))
+(define
+  dmix
+  (md/import
+    (str
+      "# Title"
+      nl
+      nl
+      "| H1 | H2 |"
+      nl
+      "| --- | --- |"
+      nl
+      "| a | b |"
+      nl
+      nl
+      "para")
+    "d"))
+(content-test
+  "table mixed types"
+  (doc-types dmix)
+  (list "heading" "table" "text"))
+
 ;; ── round-trip: import . export == identity (canonical markdown) ──
 (define
   src