docs(api): per-symbol pages, fuzzy search, deep token linking, hover cards

Rebuild the API Reference around one page per symbol and richer, verified content.

Pages & navigation
- One HTML page per symbol (kw-*, type-*, phase-*, screen-*, fn-*, annot-*, op-*)
  instead of a single scrolling page; namespace overview pages (ns-screen …
  ns-color) and a searchable index (api.html) with client-side fuzzy search.
- Sticky-header scroll offset (scroll-margin) so a jumped-to entry/param/color is
  never hidden, plus a flash highlight on the scrolled-to target.

Deep linking in every snippet & example
- Namespace members split: `Screen`→namespace page, `fill_rectangle`→method page;
  `Color`→palette page, `Charcoal`→its swatch — separately.
- Named arguments (`width:`) link to that parameter's anchor on the method page.
- Hover any token for a summary card built from the real API data (symbols.json).

Content & coverage
- Full authoritative surface documented from the compiler: every keyword, type,
  the 6 phases (Start/Input/FixedUpdate/Update/LateUpdate/Render, each its own
  page), all 22 annotations, namespace methods with parameter docs, builtins,
  the world_* reflection ABI, networking, operators — 155 symbols.
- Longer, clearer explanations; "model"/"model instance" terminology, not "entity";
  descriptive identifiers in every example (Position{column,row}, Velocity{delta_x,
  delta_y}, Health{current,maximum}, Player/Enemy) — no Pos/Seg/x/dx.
- Accuracy fixes from compiler ground-truth: world_count() takes no arg,
  world_query_next(property, cursor) arg order, event fields bind by name; dropped
  `when` and `module` (not in the self-hosted parser).

Tooling
- inventory.json + check.py: coverage guard (every symbol has a page), duplicate-
  token guard, and broken-link guard — fail CI so docs can't drift.
- validate.py: compiles every ```ludic example against bin/ludicc (158 compile).

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

docs/language/builtins/fn-clamp.md

@@ -5,8 +5,50 @@ category: builtins
 kind: builtin
 tokens: clamp
 sig: clamp(v, lo, hi) -> int
-tip: Constrain v to [lo, hi].
+tip: Constrain a value to the inclusive range [lo, hi].
 order: 9
 ---
 
-Constrain v to [lo, hi].
+Constrains a value to a range: it returns <code>lo</code> if <code>v</code> is below the range, <code>hi</code> if it is above, and <code>v</code> unchanged when it already lies within <code>[lo, hi]</code>. The classic use is keeping a moving object on screen or inside a grid, so its position can never run past the walls no matter how fast it moves. It saves you writing a pair of <code>if</code> checks by hand. Make sure <code>lo</code> is not greater than <code>hi</code>.
+
+Parameters:
+- `v` — the value to constrain
+- `lo` — the lowest allowed value (inclusive)
+- `hi` — the highest allowed value (inclusive)
+
+```ludic
+program ClampToGrid {
+  property Position { column: int = 0, row: int = 0 }
+  model Player { Position }
+
+  const GRID_WIDTH: int = 20
+  const GRID_HEIGHT: int = 15
+  const TILE_SIZE: int = 16
+
+  handler SpawnPlayer phase Start {
+    spawn Player { Position { column: 5, row: 5 } }
+  }
+
+  handler ReadInput phase Input {
+    let pressed = Input.key()
+    for (Position) in query [Position, {Player}] {
+      if pressed == 'd' { Position.column = Position.column + 1 }
+      if pressed == 'a' { Position.column = Position.column - 1 }
+      Position.column = clamp(Position.column, 0, GRID_WIDTH - 1)
+    }
+  }
+
+  handler DrawWorld phase Render {
+    Screen.clear(Color.MidnightBlue)
+    for (Position) in query [Position, {Player}] {
+      Screen.fill_rectangle(
+        x: Position.column * TILE_SIZE,
+        y: Position.row * TILE_SIZE,
+        width: TILE_SIZE,
+        height: TILE_SIZE,
+        color: Color.LimeGreen)
+    }
+    Screen.show()
+  }
+}
+```