feat(ui): unified tab-switch animation - enter-only fade in TabPanel

One 0.2s enter-only fade (opacity + 6px rise) in the kit TabPanel covers
every tab switch (M3 clean-fade pattern; CSS animation so the global
reduced-motion kill switch applies). Orders and Invoices view switchers
now render through TabPanel (also fixes their dangling aria-controls).
Removed the inconsistent bespoke framer entrances inside tab content
(CompanySettings cascade, ReceivedInvoices card). Filter-style status
tabs (Projects/Offers/Invoices) deliberately keep the refetch dim only.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/admin/ui/Tabs.tsx

@@ -2,6 +2,8 @@ import type { ReactNode } from "react";
 import MuiTabs from "@mui/material/Tabs";
 import Tab from "@mui/material/Tab";
 import Box from "@mui/material/Box";
+import { keyframes } from "@mui/system";
+import type { SxProps, Theme } from "@mui/material/styles";
 
 export interface TabDef {
   value: string;
@@ -47,15 +49,26 @@ export function Tabs({
   );
 }
 
+// The ONE tab-switch animation, app-wide: enter-only fade of the incoming
+// panel (M3 "clean fade" — old content drops instantly, no exit/slide; tabs
+// are too high-frequency for anything longer). Kept as a CSS animation so the
+// global prefers-reduced-motion kill switch in GlobalStyles neutralizes it.
+const panelEnter = keyframes({
+  from: { opacity: 0, transform: "translateY(6px)" },
+  to: { opacity: 1, transform: "none" },
+});
+
 /** Renders children only when its value matches the current tab. */
 export function TabPanel({
   value,
   current,
   children,
+  sx,
 }: {
   value: string;
   current: string;
   children: ReactNode;
+  sx?: SxProps<Theme>;
 }) {
   if (value !== current) return null;
   return (
@@ -63,7 +76,13 @@ export function TabPanel({
       role="tabpanel"
       id={panelId(value)}
       aria-labelledby={tabId(value)}
-      sx={{ pt: 2.5 }}
+      sx={[
+        {
+          pt: 2.5,
+          animation: `${panelEnter} 0.2s cubic-bezier(0.16, 1, 0.3, 1)`,
+        },
+        ...(Array.isArray(sx) ? sx : [sx]),
+      ]}
     >
       {children}
     </Box>