docs: fix section C numbering in LOTUS_TESTING.md

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

LOTUS_TESTING.md

@@ -162,13 +162,13 @@ This was the actual bug: poll buttons used undefined CSS variables, so on the **
 
 ## C. Robustness / background behavior
 
-### C2. Presence updates on tab close
+### C1. Presence updates on tab close
 
 1. Open the app, then **close the tab** (or quit the browser).
 2. From another session/device, check your **presence** shortly after.
    **Expected:** you go **offline/away** reliably (the unload now uses `fetch({keepalive})`). Previously this could be missed.
 
-### C3. Upload retry on flaky network (best-effort)
+### C2. Upload retry on flaky network (best-effort)
 
 1. In devtools → Network, set a throttle that drops/slows requests, or toggle Offline briefly **during** a file upload.
    **Expected**
@@ -176,7 +176,7 @@ This was the actual bug: poll buttons used undefined CSS variables, so on the **
 - A transient failure **retries** (up to 3×, with backoff) and the upload can still succeed once the network recovers.
 - A genuine, permanent rejection (e.g. file too large / 4xx) still **fails fast** with the usual error — it should **not** spin retrying.
 
-### C4. General timeline/composer perf (no functional regression)
+### C3. General timeline/composer perf (no functional regression)
 
 The memoization changes are invisible if correct. Just confirm **nothing broke**: