Fix the mode-choice redundancy: standardized names, deep links, compact switch

Terminology (lib/i18n-dict.ts)
- One name per mode everywhere: "Study Deck" / "Studijní balíček" and
  "Homework Solver" / "Řešitel úkolů". The library empty-state cards and the
  /create switcher now read the same, so the choice no longer changes name
  between screens.

Deep links
- Library quick actions carry the mode: /create?mode=deck and
  /homework?mode=homework.
- Both pages canonicalize: /create?mode=homework redirects to the homework
  flow and /homework?mode=deck redirects to /create, so a mode link always
  opens that mode directly.

/create
- The two bulky square cards (106px tall, wrapping/clipping "Study Deck &
  Qu…" on phones) are replaced by a compact segmented control (52px) placed
  directly above "1. Add your notes": ice pill, snowflake/sparkles icons,
  44px segments and one-line labels at 360px. The pill slides to the chosen
  segment and the route follows ~190ms later, so toggling reads as one smooth
  transition (immediate under prefers-reduced-motion).

Service worker: freezmo-v9.

Verified: mode-switch suite 26/26 (deep links, cross-mode redirects, 52px
control, 44px segments, no clipping/wrapping at 360px, "1. Add your notes" at
y=394 of 740 with the upload controls above the fold, pill slide, axe contrast,
en+cs, phone+desktop), mobile 49/49, i18n 27/27, desktop regression 73/73.
Lint + build clean.

components/UploadScreen.tsx

@@ -1,7 +1,6 @@
 "use client";
 
 import { motion } from "framer-motion";
-import Link from "next/link";
 import { useRouter } from "next/navigation";
 import { useCallback, useEffect, useMemo, useRef, useState, useSyncExternalStore } from "react";
 
@@ -33,7 +32,8 @@ import { UNORGANIZED_ID, type Difficulty } from "@/lib/schemas";
 import { upsertDeck } from "@/lib/storage";
 import { openSettings } from "@/lib/ui-events";
 import { cn, uid } from "@/lib/utils";
-import { CameraIcon, FolderIcon, IceCubeIcon, PlusIcon, SnowflakeIcon, SparklesIcon, SunIcon } from "@/components/icons";
+import { CameraIcon, FolderIcon, IceCubeIcon, PlusIcon, SnowflakeIcon, SunIcon } from "@/components/icons";
+import { ModeSwitch } from "@/components/ModeSwitch";
 import { Button, ProgressBar } from "@/components/ui";
 
 type Phase = "idle" | "preparing" | "loading" | "error";
@@ -321,39 +321,9 @@ export function UploadScreen() {
           </p>
         </section>
 
-        {/* Mode switcher: this page builds a study deck from notes; the other
-            card hands the same intake over to the homework flow. */}
-        <div className="grid grid-cols-2 gap-2.5 sm:gap-3">
-          <Link
-            href="/create"
-            aria-current="page"
-            className="card touch-target flex flex-col items-start gap-2 rounded-2xl border-accent-400/60 bg-accent-50/60 p-3 ring-2 ring-accent-400/30 sm:flex-row sm:items-center sm:gap-3 sm:p-3.5 dark:bg-accent-500/15"
-          >
-            <span
-              aria-hidden
-              className="grad-ice grid size-9 shrink-0 place-items-center rounded-xl text-[#06111f]"
-            >
-              <SnowflakeIcon className="size-5" />
-            </span>
-            <span className="min-w-0 text-[13px] font-semibold leading-snug text-[var(--text)] sm:text-[13.5px]">
-              {t("actionStudyDeck")}
-            </span>
-          </Link>
-          <Link
-            href="/homework"
-            className="card card-hover touch-target flex flex-col items-start gap-2 rounded-2xl p-3 sm:flex-row sm:items-center sm:gap-3 sm:p-3.5"
-          >
-            <span
-              aria-hidden
-              className="grid size-9 shrink-0 place-items-center rounded-xl bg-[var(--surface-sunken)] text-[var(--text-muted)]"
-            >
-              <SparklesIcon className="size-5" />
-            </span>
-            <span className="min-w-0 text-[13px] font-semibold leading-snug text-[var(--text)] sm:text-[13.5px]">
-              {t("actionHomework")}
-            </span>
-          </Link>
-        </div>
+        {/* Mode switcher: a compact segmented control. This page is the Study
+            Deck side; the other segment opens the homework flow. */}
+        <ModeSwitch current="deck" />
 
 
         {error ? (