analytical-viz: roofline tab — drop formula from step-latency header

Revert the multi-line formula annotation on the 'Latency per decode
step' header; make it a single-line markdown title matching the
'Cost per token' header on the right. Both headline plots now render
at the same height so the plot area lines up.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/analytical_visualization/app.py

@@ -2255,11 +2255,7 @@ with tab_roofline:
 
     # Plot A — Latency per decode step (undivided by B)
     with _hcol1:
-        st.markdown(
-            "**Latency per decode step**  (one forward pass)\n\n"
-            "`t_step = N·b/W + 2·N·B/C + B·S_kv·kv_bpt/W`\n\n"
-            "`     = weight_fetch + compute·B + KV_read·B`"
-        )
+        st.markdown("**Latency per decode step**  (one forward pass)")
         _figA, _axA = plt.subplots(figsize=(6, 4.2))
         _axA.plot(_xs_head, [p.weight_s * 1e3 for p in _step_pts],
                     "^-", color="#ffbe0b",