Add mod documentation in seven languages

docs/en.md

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+# Time Engine — the game clock, day and night, lights
+
+Time Engine runs the in-game clock and makes scenes follow it: the same place looks different in the morning, at noon, in the evening and at night. It also lights scenes with lamps and windows and gives you a portable lamp after dark. It is an engine mod: games such as Cthangover and the tile-map RPGs include it, and you see its work in every scene rather than as a screen of its own.
+
+## The clock
+
+The time is shown in the top-left corner of the screen. One real second is one game minute, so a game hour passes in a real minute. Some actions take game time at once — for example, cooking or crafting moves the clock forward by the recipe's time.
+
+The calendar is simplified: 30-day months and 12 months a year.
+
+## Day and night
+
+Every scene background is drawn in four moods — **morning**, **day**, **evening** and **night** — and the picture blends smoothly between them:
+
+```text
+00 ─── night ─── 04 ⇢ 06 ─ morning ─ 09 ⇢ 11 ──── day ──── 17 ⇢ 19 ─ evening ─ 21 ⇢ 22 ─── night ─── 24
+                  (⇢ = a two-hour cross-fade from one mood to the next)
+```
+
+![The same scene, the mill outside the villa in Cthangover, at 07:00, 13:00, 18:00 and 23:30: warm morning, bright noon, the evening fade, and night with lit windows.](assets/day-cycle.jpg)
+
+## Lights
+
+At night a scene is dark except for its lights. Windows, candles and lamps glow where the scene's author placed them, and each light has its own colour, radius and strength.
+
+![Night outside the villa at 23:33: only the windows glow; the lantern icon at the top of the screen is the portable lamp.](assets/night.jpg)
+
+**The portable lamp.** From 22:00 to 06:00 a lantern appears at the top of the screen. Drag it onto the scene to light the spot you want to look at.
+
+![The kitchen in Cthangover, lit by its candle and lamp.](assets/kitchen-lights.jpg)
+
+## For authors
+
+**Place lights in a scene** from its scenario with `light_set` and a list of lights. Positions are fractions of the screen (0 to 1), so they fit any window size; up to 10 lights per scene, plus the portable lamp:
+
+```scenario
+light_set [{"x":0.673,"y":0.461,"radius":500,"influence":1,"color":"#ffff00"},{"x":0.135,"y":0.315,"radius":500,"influence":1,"color":"#ffff00"}]
+```
+
+- `x`, `y` — position as a fraction of the width and height;
+- `radius` — how far the light reaches, in pixels;
+- `influence` — strength from 0 to 1;
+- `color` — a hex colour.
+
+An empty `light_set` removes the scene's lights. The light editor of Editor Tools places them with the mouse and writes this line for you. The `lighting.clear_map` scenario action turns off a scene's depth lighting when you switch to a scene that does not use it.
+
+**Night-aware backgrounds.** A background lights correctly when it has a depth map next to it, named like the picture with `_depth` (for example `bar.png` and `bar_depth.png`). A background can also have an `_albedo` companion. Without these maps, scene lights have no shape to shine on.
+
+**Other mods** read the same clock: the RPG tile map follows the same day as the backgrounds, and the time's change is announced to every mod once a game minute.
+
+## If something goes wrong
+
+1. **A scene stays bright at night.** Its background has no depth map, or the scene does not use time-of-day shading.
+2. **No lantern at night.** It appears only from 22:00 to 06:00 and only in games whose interface includes it.