web: collapse jrunner progress ticks in live_log to a single line

jrunner prints an in-place progress counter (a bare number) every batch;
read with universal newlines, each tick became its own live_log line, so a
large load stacked thousands of numbers (a 1.27M-row INSERT left 5,073
progress lines). append_run_live_log now overwrites a trailing bare-number
line with the new tick instead of appending, keeping a single current count.
Real lines (headers, "N rows written", timestamps) aren't bare numbers and
are preserved. No jrunner change.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

pipekit/repo.py

@@ -473,6 +473,24 @@ def log_run_output(run_id: int, *, jrunner_stdout: str | None = None,
 
 
 def append_run_live_log(run_id: int, text: str) -> None:
+    # jrunner emits an in-place progress counter (a bare number) every batch.
+    # stdout is read with universal newlines, so each tick arrives as its own
+    # line — appending them all stacks thousands of numbers. Collapse them:
+    # a bare-number tick overwrites a trailing bare-number line instead of
+    # appending, so the log keeps a single, current count. Real log lines
+    # (headers, "N rows written", timestamps) aren't bare numbers — untouched.
+    if text.strip().isdigit():
+        with db.connect() as c:
+            row = c.execute(
+                "SELECT live_log FROM run_log WHERE id=?", (run_id,)).fetchone()
+            cur = (row[0] if row and row[0] else "")
+            body = cur[:-1] if cur.endswith("\n") else cur
+            lines = body.split("\n") if body else []
+            if lines and lines[-1].strip().isdigit():
+                lines[-1] = text
+                c.execute("UPDATE run_log SET live_log=? WHERE id=?",
+                          ("\n".join(lines) + "\n", run_id))
+                return
     with db.connect() as c:
         c.execute(
             "UPDATE run_log SET live_log = COALESCE(live_log, '') || ? WHERE id=?",