feat(types): add Reflect.* — runtime reflection over the world schema (#20)

Runtime type reflection: enumerate properties and fields by index, resolve ids
by name, read a field's type, and get/set/has an entity's fields generically —
the foundation the issue calls out for auto-serialization, data-driven tools,
and debug/inspector overlays. Built on the existing EV2 reflection ABI plus a
new EV8 metadata-enumeration layer, all generated at compile time (a table walk,
no heavy runtime introspection), so a binary that never reflects pays nothing.

Surface (Reflect.*, aliased in emit_call.ludic over the world_* reflection ABI):
  - Reflect.prop(name) / field(prop,name)        resolve ids by name (-1 = none)
  - Reflect.prop_count() / prop_name(i)          enumerate properties
  - Reflect.field_count(prop) / field_name(prop,i) / field_type(prop,i)
                                                 enumerate a component's fields
  - Reflect.get / set / has (entity, prop, ...)  read/write/test a field by id
  - Reflect.kind(entity) / model(name)           an entity's model, by id/name

New codegen (emit_world.ludic, EV8): ludic_prop_count / prop_name /
field_count / field_name / field_type, generated the same way as ludic_prop_id
— a switch over the compile-time property/field metadata, falling through to the
mod-registered (dynamic) registries. Field names/types come straight from the
AST, so field_type reports the declared type ("int"/"fixed"/…). A program that
uses Reflect.* force-emits the reflection ABI (g_uses_reflect) so it needs no
@events of its own, exactly like Query.* (#42).

examples/library/reflect.ludic asserts 20 cases including a generic inspector
that sums every field of every component an entity has while naming none of them
— the auto-save / debug-overlay pattern end to end. Wired into x test (now 64
passed). Docs: a Reflect section + 12 per-symbol pages (positioned as an
advanced/tooling surface), inventory/coverage green. Seed reseeded; the C-free
bootstrap fixpoint holds.

Scope: this lands the reflection core and a real consumer (the generic
inspector). The generic value-tree `serialize` the proposal also sketches wants
a tagged-union/any value type from the #1 type-system work, so it is tracked as
a follow-up rather than forced in here.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tools/x/test.ludic

@@ -106,6 +106,7 @@ function cmd_test() -> int {
   feat_case("library/grid", "", "1 2 3 4 5 6 7 8 9 10 11 12 13", "grid.ludic (Grid line/flood/line_of_sight + A* pathfinding over the tilemap)")
   feat_case("library/anim", "", "1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34", "anim.ludic (Anim frame/once/pingpong/cell + Tween progress/loop/yoyo/ease/number/round/point/tint)")
   feat_case("library/query", "", "1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18", "query.ludic (Query count/first/nearest/within — ECS spatial queries over the reflection ABI)")
+  feat_case("library/reflect", "", "1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20", "reflect.ludic (Reflect prop/field enumeration + type + get/set/has/kind — runtime reflection over the world schema)")
   feat_case("library/logging", "", "0 5 2 1", "logging.ludic (Log levels, set_level/level threshold, structured fields)")
   # Os known-folders/arch and Fs.list read the BSD utsname/dirent layout, so
   # their asserted values are macOS-specific; skip off Darwin (see is_darwin).