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>

selfhost/frontend/parse.ludic

@@ -163,6 +163,7 @@ function p_postfix() -> Node {
     if is_op(".") { pi = pi + 1; let m = node(E_MEMBER); m.a = e; m.s = eat_id(); e = m
       if e.a.kind == E_ID and e.a.s == "Regex" { g_uses_regex = true }   # splice the regex runtime on demand
       if e.a.kind == E_ID and e.a.s == "Query" { g_uses_query = true }   # splice the ECS spatial-query runtime on demand
+      if e.a.kind == E_ID and e.a.s == "Reflect" { g_uses_reflect = true }   # force-emit the reflection ABI (Reflect.* reads the world schema)
     }
     else { if is_op("[") { pi = pi + 1; let lo = expr()
         if is_op("..") { pi = pi + 1; let sl = node(E_SLICE); sl.a = e; sl.b = lo; sl.c = expr(); eat_op("]"); e = sl }   # s[a..b] substring
@@ -376,6 +377,7 @@ var loaded_paths: []pointer
 var cur_dir: pointer
 var g_uses_regex: bool = false    # a program mentioned Regex.* -> splice the regex runtime
 var g_uses_query: bool = false    # a program mentioned Query.* -> splice the query runtime + reflection ABI
+var g_uses_reflect: bool = false  # a program mentioned Reflect.* -> force-emit the reflection ABI
 
 function already_loaded(full: pointer) -> bool {
   var i = 0
@@ -554,6 +556,7 @@ function parse_program() -> void {
   g_toggled_layers = new []pointer
   g_uses_regex = false
   g_uses_query = false
+  g_uses_reflect = false
   loaded_paths = new []pointer
   skipnl()
   g_game_name = "Ludic"