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/builtins/_section.md

@@ -0,0 +1,7 @@
+---
+id: builtins
+title: Builtin functions
+order: 12
+---
+
+Global functions available anywhere, beyond the namespaced APIs above.

docs/language/builtins/fn-abs.md

@@ -0,0 +1,12 @@
+---
+id: fn-abs
+name: abs
+category: builtins
+kind: builtin
+tokens: abs
+sig: abs(a) -> int
+tip: Absolute value.
+order: 8
+---
+
+Absolute value.

docs/language/builtins/fn-bytes.md

@@ -0,0 +1,12 @@
+---
+id: fn-bytes
+name: bytes / words
+category: builtins
+kind: builtin
+tokens: bytes words
+sig: bytes(n) -> ptr / words(n) -> words
+tip: Allocate a raw buffer of n bytes / n 32-bit words.
+order: 11
+---
+
+Allocate a raw buffer of n bytes / n 32-bit words.

docs/language/builtins/fn-clamp.md

@@ -0,0 +1,12 @@
+---
+id: fn-clamp
+name: clamp
+category: builtins
+kind: builtin
+tokens: clamp
+sig: clamp(v, lo, hi) -> int
+tip: Constrain v to [lo, hi].
+order: 9
+---
+
+Constrain v to [lo, hi].

docs/language/builtins/fn-font_load.md

@@ -0,0 +1,12 @@
+---
+id: fn-font_load
+name: font_load
+category: builtins
+kind: builtin
+tokens: font_load
+sig: font_load(path) -> int
+tip: Load a TrueType font and return a handle for the UI.
+order: 12
+---
+
+Load a TrueType font and return a handle for the UI.

docs/language/builtins/fn-fx.md

@@ -0,0 +1,12 @@
+---
+id: fn-fx
+name: fx / flr
+category: builtins
+kind: builtin
+tokens: fx flr
+sig: fx(n) -> fixed / flr(x) -> int
+tip: Convert between int and fixed-point.
+order: 10
+---
+
+Convert between int and fixed-point.

docs/language/builtins/fn-len.md

@@ -0,0 +1,12 @@
+---
+id: fn-len
+name: len
+category: builtins
+kind: builtin
+tokens: len
+sig: len(x) -> int
+tip: Length of a slice or string.
+order: 5
+---
+
+Length of a slice or string.

docs/language/builtins/fn-load.md

@@ -0,0 +1,12 @@
+---
+id: fn-load
+name: load
+category: builtins
+kind: builtin
+tokens: load
+sig: load() -> bool
+tip: Restore a snapshot written by save().
+order: 4
+---
+
+Restore a snapshot written by <code>save()</code>.

docs/language/builtins/fn-min.md

@@ -0,0 +1,12 @@
+---
+id: fn-min
+name: min / max
+category: builtins
+kind: builtin
+tokens: min max
+sig: min(a, b) / max(a, b) -> int
+tip: The smaller / larger of two ints.
+order: 7
+---
+
+The smaller / larger of two ints.

docs/language/builtins/fn-print.md

@@ -0,0 +1,12 @@
+---
+id: fn-print
+name: print
+category: builtins
+kind: builtin
+tokens: print
+sig: print(x)
+tip: Print an int or string, followed by a newline — for headless tests and debugging.
+order: 0
+---
+
+Print an int or string, followed by a newline — for headless tests and debugging.

docs/language/builtins/fn-push.md

@@ -0,0 +1,12 @@
+---
+id: fn-push
+name: push
+category: builtins
+kind: builtin
+tokens: push
+sig: push(slice, x)
+tip: Append to a slice.
+order: 6
+---
+
+Append to a slice.

docs/language/builtins/fn-quit.md

@@ -0,0 +1,12 @@
+---
+id: fn-quit
+name: quit
+category: builtins
+kind: builtin
+tokens: quit
+sig: quit()
+tip: Stop the game loop after this frame.
+order: 2
+---
+
+Stop the game loop after this frame.

docs/language/builtins/fn-save.md

@@ -0,0 +1,12 @@
+---
+id: fn-save
+name: save
+category: builtins
+kind: builtin
+tokens: save
+sig: save()
+tip: Serialize the entire world — every entity, property and program var — to a snapshot in one call.
+order: 3
+---
+
+Serialize the entire world — every entity, property and program <code>var</code> — to a snapshot in one call.

docs/language/builtins/fn-str.md

@@ -0,0 +1,12 @@
+---
+id: fn-str
+name: str
+category: builtins
+kind: builtin
+tokens: str
+sig: str(x) -> str
+tip: Convert an int/bool/fixed to text; a string passes through.
+order: 1
+---
+
+Convert an int/bool/fixed to text; a string passes through. Also used by <code>`{…}`</code> interpolation.