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_spawn.md

@@ -0,0 +1,30 @@
+---
+id: fn-world_spawn
+name: world_spawn
+category: ecs
+kind: builtin
+tokens: world_spawn
+sig: world_spawn(model) -> entity
+tip: Spawn an instance of a model chosen by numeric id at runtime.
+order: 50
+---
+
+<code>world_spawn</code> creates a new instance of a model chosen by numeric id and returns its `entity` handle — the reflection-ABI counterpart of the static `spawn Label { … }`. Because the model is given as an id (from `world_model_id`) rather than a name written in source, a mod or tool can decide <b>at runtime</b> which kind to create. The new instance is seeded exactly as the static spawn would seed it — every property in the model attached with default field values — after which you can set fields with `world_set`. Use the ordinary `spawn` statement in normal handler code; reach for `world_spawn` when the kind is data, not a literal.
+
+Parameters:
+- `model` — the model id to instantiate, from `world_model_id`
+
+```ludic
+program Reinforcements {
+  property Position { column: int = 0, row: int = 0 }
+  model Enemy { Position }
+
+  handler Reinforce phase Update {
+    if Input.key() == ' ' {
+      let enemy_model = world_model_id("Enemy")
+      let new_enemy = world_spawn(enemy_model)
+      Screen.status(str(new_enemy))
+    }
+  }
+}
+```