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/operators/op-arith.md

@@ -4,8 +4,14 @@ name: Arithmetic
 category: operators
 kind: operator
 sig: +  -  *  /  %
-tip: Add, subtract, multiply, integer-divide, remainder.
+tip: Add, subtract, multiply, integer-divide, and remainder — on int and fixed.
 order: 0
 ---
 
-Add, subtract, multiply, integer-divide, remainder. On <code>fixed</code> values the same symbols do fixed-point math.
+The arithmetic operators are `+` (add), `-` (subtract), `*` (multiply), `/` (divide), and `%` (remainder). On `int` values `/` is integer division that truncates and `%` gives the remainder — handy for wrapping a value or testing a period, as in `elapsed_frames % 30 == 0`. On `fixed` values the same symbols do fixed-point math (multiply and divide are scaled), and mixing an `int` with a `fixed` promotes the `int`. `*`, `/`, and `%` bind tighter than `+` and `-`, so `column * TILE_SIZE + 1` groups as expected.
+
+```ludic
+let pixel_x: int = column * TILE_SIZE + 1
+let is_even_row: bool = row % 2 == 0
+let average: int = (current_health + maximum_health) / 2
+```