Added a new 9th section 'Making It More (or Less) Sour' to frontend/80-Kitchen/sourdough-guide.html (an 8-section narrative walkthrough app w/ Read Aloud support), covering lactic vs acetic acid, cold-retard extension, starter-timing (past peak vs at peak), lower starter %, and whole-grain/rye additions -- synthesized from live web research done at USR369's request after Bake #12 closed. First attempt at the JSON insert had a bug (missing a closing brace on the prior section before appending the new one) caught by the brace/paren balance check (60 vs 59) before deploy -- rebuilt correctly (60/60, 61/61) and verified. Backed up the page first (BACKUP.php, all_pass true). Also added a missing page-inventory.html entry for this page (n:183, status DONE) since it had none -- backed that file up first too. Followed SOP-FRONTEND-LIVE-FIX.md's sequence; TASKGATE had no confident match for this task (weak candidates only) so used that SOP directly rather than writing a redundant new one, since it already covers exactly this kind of live frontend page edit.