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/hero.ludic

@@ -1,24 +1,27 @@
 # the smallest program that exercises the whole ECS pipeline
 program Hello {
 
-  property Pos { x: int = 0, y: int = 0 }
-  property Vel { dx: int = 0, dy: int = 0 }
+  property Position { column: int = 0, row: int = 0 }
+  property Velocity { delta_x: int = 0, delta_y: int = 0 }
 
-  handler Boot phase Start {
-    spawn Mob { Pos { x: 3, y: 4 }  Vel { dx: 1, dy: 0 } }
-    spawn Mob { Pos { x: 10, y: 2 } Vel { dx: 0, dy: 1 } }
+  handler SpawnEnemies phase Start {
+    spawn Enemy { Position { column: 3, row: 4 },   Velocity { delta_x: 1, delta_y: 0 } }
+    spawn Enemy { Position { column: 10, row: 2 },  Velocity { delta_x: 0, delta_y: 1 } }
   }
 
-  # a handler declares the entities it touches; the body
+  # a handler declares the models it touches; the body
   # runs once per match, each property bound by name.
-  @Queries(these: [Pos, Vel])
-  handler Move phase FixedUpdate {
-    Pos.x = Pos.x + Vel.dx
-    Pos.y = Pos.y + Vel.dy
+  @Queries(these: [Position, Velocity])
+  handler AdvancePositions phase FixedUpdate {
+    Position.column = Position.column + Velocity.delta_x
+    Position.row    = Position.row + Velocity.delta_y
   }
 
-  handler Report phase Update {
-    for (p) in query [Pos] { print(p.x)  print(p.y) }
+  handler ReportPositions phase Update {
+    for (moving) in query [Position] {
+      print(moving.column)
+      print(moving.row)
+    }
     quit()
   }
 }