feat: add catalog weapon throughput baseline

docs/DESIGN_SYSTEM.md

@@ -2595,10 +2595,33 @@ anchor scrolling and sticky-state transitions.
 #### Builder calculation modes
 
 The current Builder and shared Build pages do not expose calculation modes or
-combat assumptions. They show deterministic equipped-item totals and reserve
-conditional Talent outcomes, weapon and Skill DPS, encounter assumptions,
+combat assumptions. The Builder summary rail additionally contains one local
+experimental catalog baseline panel; shared Build pages do not render it. Keep
+the panel in the summary rail only, with two independent cards labeled `PRIMARY`
+and `SECONDARY`.
+
+Use the exact eyebrow `WEAPON OUTPUT / CATALOG BASELINE` and show the
+`EXPERIMENTAL` state. Each card displays the catalog weapon ID, selected damage,
+catalog RPM, magazine, reload, rated body-hit throughput, and magazine-cycle
+body-hit throughput. Include a visible formula and exclusions block with these
+exact formulas:
+
+- `selected damage × (RPM ÷ 60)` for rated body-hit throughput;
+- `(magazine × selected damage) ÷ ((magazine ÷ (RPM ÷ 60)) + reload seconds)`
+  for magazine-cycle body-hit throughput.
+
+The panel is evidence-only. It excludes inferred or substituted values, combat
+profiles, effects, Talents, Attribute totals, calculation profiles, accuracy,
+critical hits, headshots, enemy mitigation, target count, encounter uptime,
+rotations, and simulation. It must not present these values as actual, expected,
+or encounter DPS. When a required source value is unavailable or invalid, show
+`NOT AVAILABLE` and list the missing source fields under the metric; never
+display zero as a placeholder.
+
+The panel does not alter the planned calculation modes or full combat panels.
+Keep conditional Talent outcomes, weapon and Skill DPS, encounter assumptions,
 activation profiles, rotations, and simulation behind explicit `COMING SOON`
-panels.
+panels. Calculation modes remain planned and use these visible labels:
 
 Loadout schema version 6 retains `maximum`, `custom`, conditional state,
 encounter-assumption, and per-ability activation fields. Version 4 is obsolete