Add “Make my homework”, and finish the mobile polish pass

Homework (/homework — entry points in the drawer and on the create screen)

- Assignment intake reuses the study pipeline: pasted text, photos
  (camera/picker, compressed in the browser) and documents (PDF/DOCX/PPTX/
  ODT/text) through lib/image + lib/documents, the same vision step and the
  same language guard. Raw files never leave the device — only text and JPEG
  data URLs reach the server.
- Two large choice cards: “Just make it” returns the finished homework
  (answer only, plain text, copy + make it again); “Explain how to make this
  homework” builds an interactive guide.
- The guide is one step per screen in the study-feed snap layout:
  explanation, three progressive hints (nudge -> hint -> the answer) and an
  optional checkpoint rendered by the existing activity components (graded
  through /api/grade). The last screen assembles the solution from the step
  answers, with a copy button. Checkpoints carry xp 0 so the guide stays free
  of XP/streak chrome.
- Results live in freezmo.homework.v1 with a small history (open/delete);
  “Make it again” re-runs from the stored assignment text (the vision
  transcription when photos were used) — no original files are stored.
- The answer and the guide are written in the assignment's language, never
  translated into the UI language.

Server

- POST /api/homework: NDJSON stage events like /api/generate, the same
  http-guard, auth checked before parsing, and its own RATE_LIMIT_HOMEWORK
  (documented in .env.example + the README table).
- New prompts in lib/prompts.ts and zod schemas in lib/schemas.ts with the
  same single repair retry; TEXT_MODEL for content, VISION_MODEL only for
  photos. New shared client pieces: useNotesIntake, lib/homework store,
  lib/clipboard, and a shared NDJSON reader in lib/client-api.

Also finishing the mobile polish pass from the previous request

- Phone ice scene: the top-left orb moved behind the glass header (it sat
  behind the page heading/subtitle). The settings sheet's scroll cue is now a
  bare chevron inside a content fade (mask) instead of a chip over the status
  banner, and the API key card's note/disclosure/actions are tightened.
- theme-color now follows the in-app theme (SSR metas still fall back to the
  OS preference); apple-mobile-web-app-status-bar-style stays “default”
  because iOS fixes the status-bar text colour at launch.

Verified: 78/78 homework checks (text/photo/PDF, both modes, EN+CS, dark+light,
360/390px, copy, history persistence, storage privacy, API language, axe), plus
the existing suites re-run (mobile 47/47, pixel contrast 0 below AA, i18n 27/27,
desktop regression 72/72). Lint + build clean; service worker freezmo-v6.

components/UploadScreen.tsx

@@ -1,6 +1,7 @@
 "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";
 
@@ -32,7 +33,7 @@ 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, SunIcon } from "@/components/icons";
+import { CameraIcon, ChevronRightIcon, FolderIcon, IceCubeIcon, PlusIcon, SnowflakeIcon, SparklesIcon, SunIcon } from "@/components/icons";
 import { Button, ProgressBar } from "@/components/ui";
 
 type Phase = "idle" | "preparing" | "loading" | "error";
@@ -320,6 +321,24 @@ export function UploadScreen() {
           </p>
         </section>
 
+        {/* The other thing you can bring here: an assignment. */}
+        <Link
+          href="/homework"
+          className="card card-hover flex items-center gap-3 p-4 text-left"
+        >
+          <span
+            aria-hidden
+            className="grid size-10 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 flex-1">
+            <span className="block text-[14px] font-semibold text-[var(--text)]">{t("homework.entry")}</span>
+            <span className="block text-[12.5px] text-[var(--text-subtle)]">{t("homework.nav")} →</span>
+          </span>
+          <ChevronRightIcon className="size-4 shrink-0 text-[var(--text-subtle)]" />
+        </Link>
+
 
         {error ? (
           <div