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/site/snippets/scenes.ludic

@@ -1,7 +1,10 @@
 program SceneDemo {
   var counter: int = 0
 
-  handler Boot phase Start { counter = 0  print(1000) }
+  handler Boot phase Start {
+    counter = 0
+    print(1000)
+  }
 
   scene Title start {
     on enter { print(1) }
@@ -16,8 +19,11 @@ program SceneDemo {
   }
 
   scene Play {
-    on enter { print(3)  counter = 0 }
-    on exit  { print(4) }
+    on enter {
+      print(3)
+      counter = 0
+    }
+    on exit { print(4) }
     layer World {
       handler Step phase Update {
         counter = counter + 1
@@ -25,6 +31,8 @@ program SceneDemo {
         if counter >= 2 { quit() }
       }
     }
-    layer Hud { handler Draw phase Render { print(900) } }
+    layer Hud {
+      handler DrawHud phase Render { print(900) }
+    }
   }
 }