Switch repo to English, add i18n with EN/DE language files and first-start language selection

- in-game texts moved to lang/en.lang and lang/de.lang (key = text, placeholders)
- game logic emits message keys + args, translated at display time
- localStorage access via own miniquad JS plugin (www/dc_plugin.js)
- code comments, DESIGN.md, CREDITS.md translated; README.md added

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -0,0 +1,58 @@
+# DungeonCraft
+
+An original dungeon building & defence game that runs in the browser (Rust + [macroquad](https://github.com/not-fl3/macroquad), compiled to WebAssembly).
+
+Dig out your underground realm, claim the portal to attract creatures, keep them fed, rested and paid, fend off endless hero waves that adapt to your army – and finally destroy the Hero Gate.
+
+- 3D isometric view with a freely rotatable and tiltable camera
+- Procedural pixel art, irregular cave walls, flickering torch light
+- CP437 text-mode style interface with the DINOBYTE bitmap font
+- English and German (language files in `lang/`, easy to extend)
+
+See [DESIGN.md](DESIGN.md) for all design decisions and [CREDITS.md](CREDITS.md) for third-party assets.
+
+## Running
+
+The easiest way is Docker; the image builds the WASM file and serves it with nginx:
+
+```sh
+docker compose up -d --build
+# open http://localhost:18093
+```
+
+### Building without Docker
+
+Requirements: Rust with the `wasm32-unknown-unknown` target.
+
+```sh
+rustup target add wasm32-unknown-unknown
+cargo build --release --target wasm32-unknown-unknown
+cp target/wasm32-unknown-unknown/release/dungeoncraft.wasm www/
+cp ~/.cargo/registry/src/*/macroquad-*/js/mq_js_bundle.js www/
+python3 -m http.server 8080 -d www   # open http://localhost:8080
+```
+
+### Testing the game logic
+
+The game logic (`src/game.rs`, `src/map.rs`) does not depend on macroquad and contains a headless simulation test.
+
+## Controls
+
+| Input | Action |
+|---|---|
+| Left click / drag | Use the active tool (dig and rooms: drag a rectangle) |
+| Right click | Drop a unit from your hand |
+| Right drag, WASD, arrows, screen edge | Move the camera |
+| Middle drag, Q/E, R/F | Rotate / tilt the camera |
+| Mouse wheel | Zoom |
+| 1–9, 0, X, V | Select a tool or spell |
+| P / Space | Pause |
+| M, +/- | Sound on/off, volume |
+| G | Tile outlines on/off |
+| H | Help |
+
+## Adding a language
+
+1. Copy `lang/en.lang` to `lang/<code>.lang` and translate the texts (placeholders `{0}`, `{1}` stay as they are).
+2. Add the file to `SOURCES` in `src/i18n.rs`.
+3. Note: the DINOBYTE font only covers the CP437 character set.