analytical-viz: roofline tab — fix NameError from knob-rename refactor

Previous commit renamed slider vars (_rf_flops_mult -> _flops_mult_now,
etc.) and split _ai/_b_star into base vs scaled, but the AI-sensitivity
plot's vertical markers + caption still referenced the old names, so
loading the tab crashed with:

    NameError: name '_rf_flops_mult' is not defined

Fixed all four call sites:
- _axAI1: 'Base AI' reference line now uses _ai_base (was _ai, which
  is now the scaled value).
- _axAI2: 'Base B*' reference line uses _b_star_base; vertical
  markers use _flops_mult_now / _bw_mult_now.
- Caption 'Your knob position' uses the new names.

Grep confirms no _rf_flops_mult / _rf_bw_mult / _ai_scaled /
_b_star_scaled references remain.

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

tests/analytical_visualization/app.py

@@ -2427,8 +2427,8 @@ with tab_roofline:
                  color="#3a86ff", linewidth=2, label="Scale FLOPs")
     _axAI1.plot(_ai_mults, [p.ai for p in _ai_bw_pts], "s-",
                  color="#d90429", linewidth=2, label="Scale HBM BW")
-    _axAI1.axhline(_ai, color="#2e7d32", linestyle=":",
-                    label=f"Base AI = {_ai:.1f}")
+    _axAI1.axhline(_ai_base, color="#2e7d32", linestyle=":",
+                    label=f"Base AI = {_ai_base:.1f}")
     _axAI1.axvline(1.0, color="#888", linestyle=":", alpha=0.5)
     _axAI1.set_xscale("log", base=2)
     _axAI1.set_yscale("log")
@@ -2442,12 +2442,12 @@ with tab_roofline:
                  color="#3a86ff", linewidth=2, label="Scale FLOPs")
     _axAI2.plot(_ai_mults, [p.b_star for p in _ai_bw_pts], "s-",
                  color="#d90429", linewidth=2, label="Scale HBM BW")
-    _axAI2.axhline(_b_star, color="#2e7d32", linestyle=":",
-                    label=f"Base B* = {_b_star:.0f}")
-    _axAI2.axvline(_rf_flops_mult, color="#3a86ff", linewidth=1.2,
-                    alpha=0.5, label=f"FLOPs × {_rf_flops_mult:.2f}")
-    _axAI2.axvline(_rf_bw_mult, color="#d90429", linewidth=1.2,
-                    alpha=0.5, label=f"BW × {_rf_bw_mult:.2f}",
+    _axAI2.axhline(_b_star_base, color="#2e7d32", linestyle=":",
+                    label=f"Base B* = {_b_star_base:.0f}")
+    _axAI2.axvline(_flops_mult_now, color="#3a86ff", linewidth=1.2,
+                    alpha=0.5, label=f"FLOPs × {_flops_mult_now:.2f}")
+    _axAI2.axvline(_bw_mult_now, color="#d90429", linewidth=1.2,
+                    alpha=0.5, label=f"BW × {_bw_mult_now:.2f}",
                     linestyle="--")
     _axAI2.set_xscale("log", base=2)
     _axAI2.set_yscale("log")
@@ -2466,10 +2466,10 @@ with tab_roofline:
         f"raises AI linearly (more compute per byte). Scaling **HBM BW** "
         f"lowers AI (more bytes to feed per FLOP). "
         f"**Right**: B\\* moves in the same direction as AI. "
-        f"**Your knob position**: FLOPs × {_rf_flops_mult:.2f}, "
-        f"BW × {_rf_bw_mult:.2f} → **AI = {_ai_scaled:.2f}**, "
-        f"**B\\* = {_b_star_scaled:.0f}** (vs base AI {_ai:.1f}, "
-        f"B\\* {_b_star:.0f})."
+        f"**Your knob position**: FLOPs × {_flops_mult_now:.2f}, "
+        f"BW × {_bw_mult_now:.2f} → **AI = {_ai:.2f}**, "
+        f"**B\\* = {_b_star:.0f}** (base AI {_ai_base:.1f}, "
+        f"B\\* {_b_star_base:.0f})."
     )
 
     st.divider()