fix(dashboard): equal-height cards — stretch + fill instead of ragged

The dashboard content grids used alignItems:"start", so cards in a row sized to
their own content (ragged bottoms). Switch to alignItems:"stretch" so each row
shares one height, and make the wrapped cards actually fill the cell:

- DashProfile / DashSessions: motion-div + Card height:100% (the inner card was
  shorter than its stretched cell).
- Right column (Aktivní projekty + Nabídky): cards flex:1 so the stacked pair
  fills the column to match the neighbouring single cards.

CSS-only; no logic change. tsc clean, lint 0, 669 tests pass. Verified live via
Playwright (3-col row cells equal at 607; bottom 2-col cards equal at 257).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/admin/components/dashboard/DashSessions.tsx

@@ -132,8 +132,9 @@ export default function DashSessions() {
         initial={reduce ? false : { opacity: 0, y: 12 }}
         animate={reduce ? undefined : { opacity: 1, y: 0 }}
         transition={{ duration: 0.25, delay: 0.15 }}
+        style={{ height: "100%" }}
       >
-        <Card sx={{ display: "flex", flexDirection: "column" }}>
+        <Card sx={{ display: "flex", flexDirection: "column", height: "100%" }}>
           <Box
             sx={{
               display: "flex",