Build all apps from Markdown content; Compose Desktop replaces GTK on Linux and Windows

- content/ + scripts/build-content.py produce content.json for every app
- stable lesson IDs with one-time progress migration (Swift, Kotlin)
- shared answer-check tests (tests/answers.json) for Kotlin and Swift
- android/desktop: Compose app with updater, speech and GTK progress import
- CI packages AppImage and Windows zip with ProGuard, runs the tests

Co-authored-by: Cursor <cursoragent@cursor.com>

content/anglictina/1-rocnik/04-muj-pokoj.md

@@ -0,0 +1,78 @@
+---
+id: anglictina-1-muj-pokoj
+puvodni: en.1.4
+nazev: Můj pokoj
+popis: There is / there are a předložky místa. Krátký popis a kvíz.
+---
+
+# Výklad
+
+## Co v pokoji je
+*There is*
+
+- There is a desk under the window. There are two chairs.
+- Zápor: There isn't a TV. There aren't any posters.
+- Otázka: Is there a lamp? Are there any books?
+- Předložky: in, on, under, next to, between, behind, in front of.
+
+> Tip: there is pro jedno, there are pro více. There je formální podmět.
+
+## Popis místa
+*Psaní*
+
+- Začněte velikostí a světlem: small but bright.
+- Každá věta ať má věc a místo: The bag is under the chair.
+- Střídejte there is a there are, ať text není seznam.
+- Na konci jedna osobní věta: I like it because it is quiet.
+
+> Tip: jděte od velkého k malému, od dveří k oknu.
+
+
+# Psaní
+
+Describe your room in at least 30 words. Say what is in it and where things are. Use on and a piece of furniture such as a bed, and mention a window.
+
+## Vzorová odpověď
+
+My room is small but bright. There is a bed next to the window and a wooden desk under a shelf. My books are on the desk and my school bag is under the chair. There are two posters on the wall. I like the room because it is quiet in the evening.
+
+## Musí obsahovat
+
+- bed
+- window
+- on
+
+## Minimum slov
+
+30
+
+
+# Kvíz
+
+## The lamp is ___ the desk.
+- under
+- [x] on
+- between
+- at
+> Lampa stojí na desce: on.
+
+## There ___ a big window.
+- are
+- [x] is
+- be
+- have
+> Jedno okno: there is.
+
+## There ___ two posters on the wall.
+- is
+- [x] are
+- has
+- been
+> Dva plakáty: there are.
+
+## The cat is sleeping ___ the bed.
+- [x] under
+- next
+- between to
+- at to
+> Pod postelí: under the bed.