shell-redesign V1 attempt-3 Phase 3 BOUNCE-FIX follow-on: seat detail double-padding

Founder reported: node detail page (e.g.,
/topology/seat/$rigId/$logicalId) was pushed too far right at desktop
1440x900. The 'DISCOVERY.INTAKE-ROUTER' detail panel rendered far right
of the Explorer's right edge instead of anchored at the workspace
left offset.

Root cause: double-padding from Class B's `paddingLeft:
var(--workspace-left-offset)` on <main>, combined with legacy
WorkspacePage (consumed by LiveNodeDetails) ALSO reading the same
--workspace-left-offset via `lg:pl-[var(--workspace-left-offset,0px)]`.

Net effect: <main> padded by anchor (21rem); WorkspacePage inside
LiveNodeDetails added another 21rem on top → content shifted ~42rem
right (about half the viewport).

Fix: reset --workspace-left-offset and --workspace-right-offset to 0px
on the inner div that wraps {children} inside <main>. This way:

- <main> reads the OUTER var (set on <main> via workspaceStyle) →
  applies its own paddingLeft.
- Children (legacy WorkspacePage consumers + Phase 3 destinations)
  read the INNER var (overridden to 0) → no double padding.

Phase 3 destinations (Dashboard / TopologyTreeView / etc.) don't use
the var directly; they were already fine. The fix only neutralizes
double-padding for legacy children inheriting WorkspacePage layout.

Visual verification at /topology/seat/$rigId/discovery.intake-router
1440x900: detail panel anchored just past the Explorer's right edge
(at the workspace left offset = 21rem); sub-tabs IDENTITY/AGENT_SPEC/
STARTUP/TRANSCRIPT also anchored. (Inner panel renders an HTTP 404
because /api/inventory route on shipped daemon doesn't have entries
for synthetic test seat ID — separate data-availability issue, not
layout.)

Tests: 634/636 PASS unchanged (no regression; pre-existing
library-review + skipped seat-scope).
Build: ✓ in 1.99s.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

packages/ui/src/components/AppShell.tsx

@@ -534,7 +534,19 @@ function AppShellInner({ children }: AppShellProps) {
                   paddingLeft: `var(--workspace-left-offset, 0px)`,
                 }}
               >
-                <div key={pathname} className="relative z-10 route-enter flex-1 flex flex-col">
+                {/* Reset the workspace offset CSS vars to 0 inside main so that
+                    legacy children (e.g., LiveNodeDetails → WorkspacePage which
+                    also reads var(--workspace-left-offset) for its own padding)
+                    don't double-pad. The padding is already applied at <main>
+                    above; child surfaces should treat their own offset as 0. */}
+                <div
+                  key={pathname}
+                  className="relative z-10 route-enter flex-1 flex flex-col"
+                  style={{
+                    "--workspace-left-offset": "0px",
+                    "--workspace-right-offset": "0px",
+                  } as CSSProperties}
+                >
                   {children}
                 </div>
               </main>