Initial import of LogDarioSeq baseline

Establishes version control for the personal Logseq DB fork before
starting the server-client architecture migration and domain features
described in docs/agent-guide and the approved implementation plan.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

cli/lib/vec.ml

@@ -0,0 +1,14 @@
+include Rrbvec
+
+let string_concat sep values = String.concat sep (to_list values)
+
+let split_on_char sep value =
+  let len = String.length value in
+  let rec loop start index acc =
+    if index = len then push_back acc (String.sub value start (index - start))
+    else if value.[index] = sep then
+      let acc = push_back acc (String.sub value start (index - start)) in
+      loop (index + 1) (index + 1) acc
+    else loop start (index + 1) acc
+  in
+  loop 0 0 empty