Lower syllable pipe-ratio threshold from 5% to 1%

Real dictionary pages have only ~3% OCR-detected pipes because the thin
syllable divider lines are hard for OCR to read. The primary false-positive
guard (article_col_index check) already blocks synonym dictionaries.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

klausur-service/backend/cv_syllable_detect.py

@@ -200,10 +200,9 @@ def insert_syllable_dividers(
     For dictionary pages: process all content column cells, strip existing
     pipes, merge pipe-gap spaces, and re-syllabify using pyphen.
 
-    Pre-check: at least 5% of content cells must already contain ``|`` from
-    OCR.  This guards against false-positive dictionary detection on pages
-    like synonym dictionaries or alphabetical word lists that have no actual
-    syllable divider lines.
+    Pre-check: at least 1% of content cells must already contain ``|`` from
+    OCR.  This guards against pages with zero pipe characters (the primary
+    guard — article_col_index — is checked at the call site).
 
     Returns the number of cells modified.
     """
@@ -227,10 +226,10 @@ def insert_syllable_dividers(
 
     if total_col_cells > 0:
         pipe_ratio = cells_with_pipes / total_col_cells
-        if pipe_ratio < 0.05:
+        if pipe_ratio < 0.01:
             logger.info(
                 "build-grid session %s: skipping syllable insertion — "
-                "only %.1f%% of cells have existing pipes (need >=5%%)",
+                "only %.1f%% of cells have existing pipes (need >=1%%)",
                 session_id, pipe_ratio * 100,
             )
             return 0