docs: automated documentation pipeline (per-symbol source → pages)

Replace the hardcoded landing page and minimal reference with a generated
documentation site driven by a single source of truth.

- docs/language/**: one file per symbol (93 keywords/types/builtins/namespace
  methods/operators/annotations), each with front-matter (id, kind, tokens,
  sig, tip) + description + a ```ludic example. Seeded by exploding the former
  inline SECTIONS list; these files are now the source of truth.
- docs/site/: site.json (editable hero/features/showcase/messaging, not
  hardcoded) + snippets/*.ludic (real programs shown on the landing page).
- tools/docgen/gen.py: generates index.html, api.html, ludic-highlight.js and
  symbols.json. The highlighter's symbol tables, hover tips and jump anchors
  are GENERATED from the per-symbol files — add a symbol and it is recognized,
  tipped and linked in every snippet automatically. Python stdlib only.
- tools/docgen/check.py: verifies the pages contract + that no snippet token
  links to a missing reference anchor.
- .forgejo/workflows/docs.yml: rebuilds and publishes to the pages branch on
  every push to main touching the docs sources.

Consumes the new Screen.*/Color.*/named-arg API and the 221-color palette.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/language/structure/_section.md

@@ -0,0 +1,7 @@
+---
+id: structure
+title: Program structure
+order: 0
+---
+
+The shape of a Ludic program: one <code>program</code> block holding declarations.

docs/language/structure/kw-const.md

@@ -0,0 +1,12 @@
+---
+id: kw-const
+name: const
+category: structure
+kind: keyword
+tokens: const
+sig: const NAME: T = value
+tip: A compile-time constant.
+order: 5
+---
+
+A compile-time constant. Folds directly into the code — no storage, no cost.

docs/language/structure/kw-extern.md

@@ -0,0 +1,12 @@
+---
+id: kw-extern
+name: extern
+category: structure
+kind: keyword
+tokens: extern
+sig: extern fn name(a: T) -> R = "symbol"
+tip: Bind a name to an external C-ABI symbol — the seam for platform and library calls.
+order: 12
+---
+
+Bind a name to an external C-ABI symbol — the seam for platform and library calls.

docs/language/structure/kw-fn.md

@@ -0,0 +1,12 @@
+---
+id: kw-fn
+name: fn
+category: structure
+kind: keyword
+tokens: fn
+sig: fn name(a: T, b: T) -> R { … }
+tip: A function.
+order: 8
+---
+
+A function. Call it positionally or with named arguments: <code>name(a: 1, b: 2)</code>.

docs/language/structure/kw-handler.md

@@ -0,0 +1,16 @@
+---
+id: kw-handler
+name: handler
+category: structure
+kind: keyword
+tokens: handler
+sig: handler Name phase P { … }
+tip: A block of code the engine runs every frame during phase P.
+order: 3
+---
+
+A block of code the engine runs every frame during phase <code>P</code>. With a query, the body runs once per matching entity.
+
+```ludic
+handler Move phase Update { … }
+```

docs/language/structure/kw-import.md

@@ -0,0 +1,12 @@
+---
+id: kw-import
+name: import
+category: structure
+kind: keyword
+tokens: import
+sig: import "file.ludic"
+tip: Splice another Ludic file into this program.
+order: 10
+---
+
+Splice another Ludic file into this program. Paths resolve relative to the importer; re-imports are free.

docs/language/structure/kw-let.md

@@ -0,0 +1,12 @@
+---
+id: kw-let
+name: let
+category: structure
+kind: keyword
+tokens: let
+sig: let name = value
+tip: An immutable binding, scoped to the block it appears in.
+order: 7
+---
+
+An immutable binding, scoped to the block it appears in.

docs/language/structure/kw-model.md

@@ -0,0 +1,16 @@
+---
+id: kw-model
+name: model
+category: structure
+kind: keyword
+tokens: model
+sig: model Name { PropA, PropB, … }
+tip: A named bundle of properties, so an entity that always travels together is spawned by one name.
+order: 2
+---
+
+A named bundle of properties, so an entity that always travels together is spawned by one name.
+
+```ludic
+model Player { Health, Shield }
+```

docs/language/structure/kw-module.md

@@ -0,0 +1,12 @@
+---
+id: kw-module
+name: module
+category: structure
+kind: keyword
+tokens: module
+sig: module Name { @export fn … }
+tip: Build a shared library of plain C-ABI symbols instead of an executable.
+order: 11
+---
+
+Build a shared library of plain C-ABI symbols instead of an executable.

docs/language/structure/kw-phase.md

@@ -0,0 +1,12 @@
+---
+id: kw-phase
+name: phase
+category: structure
+kind: phase
+tokens: Start Input Update FixedUpdate Render
+sig: phase Start | Input | Update | FixedUpdate | Render
+tip: When a handler runs.
+order: 4
+---
+
+When a handler runs. <b>Start</b> once at boot; <b>Input</b> reads the keyboard; <b>Update</b> is the per-frame step; <b>FixedUpdate</b> is the deterministic fixed-step; <b>Render</b> draws the frame.

docs/language/structure/kw-program.md

@@ -0,0 +1,12 @@
+---
+id: kw-program
+name: program
+category: structure
+kind: keyword
+tokens: program
+sig: program Name { … }
+tip: The top-level unit.
+order: 0
+---
+
+The top-level unit. A program compiles to one native game; everything else lives inside it.

docs/language/structure/kw-property.md

@@ -0,0 +1,16 @@
+---
+id: kw-property
+name: property
+category: structure
+kind: keyword
+tokens: property
+sig: property Name { field: T = default, … }
+tip: A component: a named record of fields an entity can carry.
+order: 1
+---
+
+A component: a named record of fields an entity can carry. Fields have a type and a default.
+
+```ludic
+property Pos { x: int = 0, y: int = 0 }
+```

docs/language/structure/kw-return.md

@@ -0,0 +1,12 @@
+---
+id: kw-return
+name: return
+category: structure
+kind: keyword
+tokens: return
+sig: return value
+tip: Return from a function.
+order: 9
+---
+
+Return from a function.

docs/language/structure/kw-var.md

@@ -0,0 +1,16 @@
+---
+id: kw-var
+name: var
+category: structure
+kind: keyword
+tokens: var
+sig: var name: T = value
+tip: A mutable binding.
+order: 6
+---
+
+A mutable binding. At program scope it is your game's persistent, named state — the modern replacement for numeric registers.
+
+```ludic
+var score: int = 0
+```