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/ecs/fn-world_kind.md

@@ -0,0 +1,35 @@
+---
+id: fn-world_kind
+name: world_kind
+category: ecs
+kind: builtin
+tokens: world_kind
+sig: world_kind(target) -> int
+tip: The model id of an instance — which kind of thing it is.
+order: 50
+---
+
+<code>world_kind</code> returns the model id of a given instance — that is, which kind of thing it is — as an `int`. Compare the result against ids from `world_model_id` to branch generically on an instance's kind without knowing it at compile time, the reflection-ABI stand-in for the `{Model}` tag filter in a static `query`. It is the natural partner of `world_query_next` when you walk instances by id and need to tell players from enemies. Pass the instance handle you want to classify.
+
+Parameters:
+- `target` — the model instance to classify, an `entity` handle
+
+```ludic
+program Classify {
+  property Position { column: int = 0, row: int = 0 }
+  model Player { Position }
+  model Enemy  { Position }
+
+  handler Boot phase Start {
+    spawn Hero  { Position { column: 2, row: 2 } }
+    spawn Grunt { Position { column: 8, row: 2 } }
+  }
+
+  handler Inspect phase Update {
+    let enemy_model = world_model_id("Enemy")
+    for (position) in query [Position] {
+      if world_kind(self()) == enemy_model { Screen.status("found an enemy") }
+    }
+  }
+}
+```