Fonts: letter spacing for text

- Fonts has a new paragraph on the Letter spacing property, with the
  conversion from em: -0.03em at size 216 is -6.5.
- Concepts lists letterSpacing among the text properties.
- Development counts 2066 checks (30f-ii is new).

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

Concepts.md

@@ -8,7 +8,7 @@
 | **State machine** | A named set of **states**, edited as nodes in its own tab. A behavior puts it into a state with `Set state`, moves it along a named transition with `State transition` and branches on it with `State branch`. Its **Scope** says where the current state lives: **Local** gives every behavior instance one of its own, **Global** keeps a single one for the whole run. See [State machines](State-machines). |
 | **Shader** | A node graph that becomes the GLSL a sprite is drawn with, edited in its own tab. A sprite, a text or a particle source wears it through `shader`; the numbers the graph declares are rows below that dropdown. A **shader function** is a part of such a graph kept on its own and used as a node in other shaders. See [Shaders](Shaders). |
 | **Particles** | A node graph that says what *one* particle is as a function of its age and of a random number drawn once for it — no forces, no simulation. Unlike the other graph assets it **is** placeable: the object made from it is a source, whose rows say how many go out and for how long they live. Because a particle is a formula, the same second always draws the same picture and the tab's slider can jump to any of them exactly. See [Particles](Particles). |
-| **Text** | An asset that draws a line of text (`text`, `font`, `fontSize`, `color`, `align`) — titles, HUD readouts, button labels. Its content is an ordinary property, so a `Properties` node of type Text with `text` switched to Set changes it while playing. |
+| **Text** | An asset that draws a line of text (`text`, `font`, `fontSize`, `letterSpacing`, `color`, `align`) — titles, HUD readouts, button labels. Its content is an ordinary property, so a `Properties` node of type Text with `text` switched to Set changes it while playing. |
 | **Enabled** | Every placeable asset has the switch `enabled` (default on). A disabled object is not drawn, does not collide and its behavior does not run — **and neither does anything parented below it**. Switching one instance off is a normal override, which makes a container a *screen*: switch it on to show it, off to hide it. From a graph, `Properties` with `enabled` switched to Set does it, and `Is enabled` asks (including the parents); a behavior hears the switch as `On enable` / `On disable`. |
 | **Scene object** | An asset placed into a scene: a link to the asset + a **position** (`x`, `y`, `z`) + sparse **overrides** of the asset's properties + an optional **parent** (another object of the scene). Drawn objects also carry **transform** rows (scale, rotation, mirror) — properties like any other, and they cascade to children the way a position does (see [Scene editing](Scene-editing)). Scenes cannot be placed. |
 | **Container** | A reusable group ("prefab"): the asset holds a **template** of objects (asset link, local position, overrides, parent links) centred on its origin. Placing a container stores the container object **and nothing else** — its content is resolved from the template on every read, so a template edit reaches every instance at once. **Create container** turns the current selection into such an asset: the selected objects move into the template and the scene keeps one placed container at their centre (world positions unchanged). The template is edited in the **Container** tab (see [Containers](Containers)) or from an instance through **Apply to container**. |

Development.md

@@ -21,7 +21,7 @@ php tests/php/releases.test.php                               # the release stor
 php tests/php/files.test.php                                  # uploaded files in a folder per account (#344), the same way
 php tests/php/videos.test.php                                 # the video store, its queue and the worker (#402), with the
                                                               #   real ffmpeg: the CI image and feuerwerk-video have it
-node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 2065 editor checks, screenshots in /tmp/gm-e2e-*.png
+node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 2066 editor checks, screenshots in /tmp/gm-e2e-*.png
 GM_STEPS=20 node tools/e2e.mjs                                # or 1-12, or 6,20 — a subset while working on one step
 ./e2e.sh start [GM_STEPS]                                     # the same run detached, see below
 ./e2e.sh status                                               # live progress, or the last run's result

Fonts.md

@@ -38,6 +38,11 @@ while playing — all three go through one place (`WorldViewport.syncText`, whic
 `TextPicture`: glyphs rasterised into a picture of the text's own, drawn like a sprite so a shader
 can be worn — see [Shaders](Shaders)).
 
+**Letter spacing.** Below Font size, in the same units: what is added between two characters,
+so a text of ten characters grows by nine times the value. Negative draws them closer, which is
+how a design's tracking in em carries over: -0.03em at a font size of 216 is -6.5. The spacing
+counts into the text's footprint, so selecting, picking and "Add collider" follow it.
+
 **Filter.** A font asset has one row, **Filter**, the same as a texture's: **Linear** (the default)
 draws the glyphs smooth and renders them again, sharper, as the view zooms in. **Nearest** is for
 pixel fonts: the glyphs end up at one texel per world unit and are magnified without smoothing,