fix(mobile): plan landscape collapse + person picker, Odin page scroll, plan toolbar stacking

- PlanGrid maxHeight gets a 360px floor: calc(100dvh - 240px) left
  <160px in phone landscape and the rows vanished under the sticky
  header
- Phones get a person picker above the plan grid (one column at a
  time, defaults to the logged-in user) - the multi-person grid never
  fit a portrait viewport; desktop unchanged
- Odin chat height uses 100svh instead of 100dvh: dvh grows live as
  Android Chrome collapses its address bar, so the page always allowed
  a chrome-height scroll; svh sizes for the bar-visible viewport
  (verified zero overflow at 390x844 via Playwright)
- Plan toolbar stacks into full-width rows on xs (headerActionsSx
  pattern from the detail pages); Dnes/arrows and Tyden/Mesic stay
  paired on one row each

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

src/admin/components/PlanGrid.tsx

@@ -1,6 +1,7 @@
-import { useMemo } from "react";
+import { useMemo, useState } from "react";
 import type { CSSProperties } from "react";
-import { styled } from "@mui/material/styles";
+import { styled, useTheme } from "@mui/material/styles";
+import useMediaQuery from "@mui/material/useMediaQuery";
 import Box from "@mui/material/Box";
 import {
   GridData,
@@ -11,7 +12,8 @@ import {
 } from "../lib/queries/plan";
 import type { Project } from "../lib/queries/projects";
 import PlanRangeChips from "./PlanRangeChips";
-import { LoadingState } from "../ui";
+import { LoadingState, Select, Field } from "../ui";
+import { useAuth } from "../context/AuthContext";
 import { fonts } from "../theme";
 
 /**
@@ -30,7 +32,10 @@ const PlanGridRoot = styled(Box)(({ theme }) => ({
   border: `1px solid ${theme.vars!.palette.divider}`,
   borderRadius: 14,
   boxShadow: theme.shadows[2],
-  maxHeight: "calc(100dvh - 240px)",
+  // Never collapse below ~5 rows: on a phone in LANDSCAPE 100dvh is only
+  // ~360-400px, so the bare calc left <160px and the cells disappeared
+  // under the sticky header. The grid scrolls internally either way.
+  maxHeight: "max(calc(100dvh - 240px), 360px)",
   isolation: "isolate",
 
   "& .plan-grid": {
@@ -464,6 +469,15 @@ export default function PlanGrid({
   pulseKey,
   onCellClick,
 }: Props) {
+  const theme = useTheme();
+  // Phone layout: the multi-person grid doesn't fit a portrait viewport, so
+  // a person picker shows ONE column at a time (Datum + selected person).
+  // Desktop/tablet keeps all columns.
+  const isMobile = useMediaQuery(theme.breakpoints.down("sm"));
+  const { user: authUser } = useAuth();
+  // null = "no explicit choice yet" → defaults to the logged-in user when
+  // they are in the plan, else the first person.
+  const [mobileUserId, setMobileUserId] = useState<number | null>(null);
   const today = useMemo(() => todayIso(), []);
   const catMap = useMemo(() => categoryMap(categories), [categories]);
   // Index projects by id once per projects change instead of a linear
@@ -483,7 +497,15 @@ export default function PlanGrid({
   );
 
   if (!data) return <LoadingState />;
-  const users = data.users;
+  const allUsers = data.users;
+  // Mobile: narrow to the picked person (derived, not stored — a stale pick
+  // after the user list changes falls back gracefully).
+  const mobileUser =
+    allUsers.find((u) => u.id === mobileUserId) ??
+    allUsers.find((u) => u.id === authUser?.id) ??
+    allUsers[0];
+  const users =
+    isMobile && allUsers.length > 1 && mobileUser ? [mobileUser] : allUsers;
   // pulseKey?.nonce is included in the data-pulse attribute so a second
   // mutation on the same cell re-triggers the animation (CSS animations
   // don't restart unless the keyframe applies to a fresh element/class
@@ -493,6 +515,21 @@ export default function PlanGrid({
     : undefined;
 
   return (
+    <>
+      {isMobile && allUsers.length > 1 && (
+        <Box sx={{ mb: 1.5 }}>
+          <Field label="Osoba">
+            <Select
+              value={String(mobileUser?.id ?? "")}
+              onChange={(value) => setMobileUserId(Number(value))}
+              options={allUsers.map((u) => ({
+                value: String(u.id),
+                label: u.full_name,
+              }))}
+            />
+          </Field>
+        </Box>
+      )}
       <PlanGridRoot data-pulse={pulseAttr}>
         <table className="plan-grid">
           {/* The colgroup is what actually controls column width in a
@@ -644,5 +681,6 @@ export default function PlanGrid({
           </tbody>
         </table>
       </PlanGridRoot>
+    </>
   );
 }

src/admin/components/odin/OdinChat.tsx

@@ -422,7 +422,12 @@ export default function OdinChat() {
   return (
     <Box
       sx={{
-        height: "calc(100dvh - 100px)",
+        // svh (NOT dvh): dvh grows live as the mobile URL bar collapses, so a
+        // dvh-sized full-height layout always lets the page scroll by the
+        // browser-chrome height. svh sizes for the bar-visible viewport — the
+        // page never scrolls and the chat's message list scrolls internally.
+        // Desktop: svh === vh.
+        height: "calc(100svh - 100px)",
         display: "flex",
         border: 1,
         borderColor: "divider",

src/admin/pages/PlanWork.tsx

@@ -667,19 +667,29 @@ export default function PlanWork() {
         </Box>
       )}
 
+      {/* Mobile: stacked full-width rows (same pattern as headerActionsSx on
+          the detail pages); sm+ keeps the single wrapping toolbar row. The
+          paired controls (Dnes/arrows, Týden/Měsíc) stay together as one
+          full-width row each. */}
       <Box
         sx={{
           display: "flex",
-          flexWrap: "wrap",
-          alignItems: "center",
+          flexDirection: { xs: "column", sm: "row" },
+          flexWrap: { sm: "wrap" },
+          alignItems: { xs: "stretch", sm: "center" },
           gap: 1.5,
           mb: 2,
         }}
       >
         {/* Nav buttons grouped so they stay on one row when the toolbar
               wraps on mobile. */}
-        <Box sx={{ display: "inline-flex", gap: 1 }}>
-          <Button variant="outlined" color="inherit" onClick={goToToday}>
+        <Box sx={{ display: "flex", gap: 1 }}>
+          <Button
+            variant="outlined"
+            color="inherit"
+            onClick={goToToday}
+            sx={{ flex: { xs: 1, sm: "0 0 auto" } }}
+          >
             Dnes
           </Button>
           <Button
@@ -701,8 +711,8 @@ export default function PlanWork() {
         </Box>
         <Box
           sx={{
-            flex: 1,
-            minWidth: 220,
+            flex: { sm: 1 },
+            minWidth: { sm: 220 },
             display: "flex",
             justifyContent: "center",
           }}
@@ -727,7 +737,11 @@ export default function PlanWork() {
         <Box
           role="group"
           aria-label="Měřítko zobrazení"
-          sx={{ display: "inline-flex", gap: 1 }}
+          sx={{
+            display: "flex",
+            gap: 1,
+            "& > button": { flex: { xs: 1, sm: "0 0 auto" } },
+          }}
         >
           <Button
             variant={view === "week" ? "contained" : "outlined"}