Networking N2–N6, and a fully C-free toolchain

Implement the rest of NETWORKING-DESIGN.md (N2–N6) and eliminate every
`.c` file from the repo. clang remains only the LLVM-IR assembler; no C
is compiled anywhere.

Networking (selfhost/emit_net.ludic + parser/emit changes):
- N2 @Sync: per-model serialize/apply + by-kind dispatchers; POD-scalar
  compile error and empty-participation warning; selective replication.
- N3 @Owned: @L_owner array + owner/set_owner/is_owner; owners snapshot.
- N4 @ToServer/@ToClients remote events: framed net_send + net_pump re-emit.
- N5 @Server/@Predicted role guards + drivable sim (tick_fixed/tick_render,
  entry-owns-the-loop).
- Built-in loopback transport so multiplayer runs with zero foreign code;
  extern fn net_send/net_poll still overrides it for a real socket.
- N6 blessed runtime (examples/net_rt.ludic) + end-to-end demo (net_demo).
- Fix: llty("entity") is now i32 (entities are i32 handles), so let e = self().

C elimination:
- Networking + foreign-mod-ABI tests rewritten as self-contained pure-Ludic
  programs (examples/net_*, world_*, mod_events, scoped); tests/ removed.
- Reflection ABI exposed to Ludic as world_* builtins (Ludic-to-Ludic modding).
- Formatter rewritten C→Ludic: tools/ludic-tools/fmt.ludic.
- Language server rewritten C→Ludic: tools/ludic-tools/lsp.ludic (lexer, index
  parser, cross-file workspace resolver, JSON, all LSP handlers).
- Obsolete migrate_*.c codemods deleted; ludic_syntax.h kept as vocabulary data.

Suites: ./test.sh 44/44, ./tools/test-tools.sh 28/28 (LSP 42/42), fixpoint holds.

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

examples/promote.ludic

@@ -0,0 +1,32 @@
+# promote.ludic — EV1: `@Public` promotes a lifecycle hook to a public event.
+#
+# Marking a lifecycle hook `@Public` makes its fire site ALSO emit an event named
+# for the moment — `model_<M>_spawn`, `model_<M>_despawn` — carrying the entity
+# (and, for despawn, the EndReason). Anything can then subscribe: a native
+# listener with `@On(model_Enemy_spawn)`, or a foreign mod binding
+# `ludic_on_model_Enemy_spawn` over the C ABI. The game's own lifecycle becomes
+# the modding surface, with no hand-written `emit` in the hook body.
+#
+# Running it prints:  100 101 200 201
+program Promote {
+  property Health { hp: int = 0, max: int = 100 }
+  model Enemy { Health }
+
+  @Public @OnSpawn(Enemy)   handler Init  { Health.hp = Health.max }   # -> model_Enemy_spawn
+  @Public @OnDespawn(Enemy) handler Clean { }                          # -> model_Enemy_despawn
+
+  # Listeners on the promoted events. These read the generated payload (entity,
+  # and reason for despawn) by name — exactly what a foreign mod receives.
+  @On(model_Enemy_spawn)   handler Spawned { print(entity + 100) }
+  @On(model_Enemy_despawn) handler Died    { print(entity + reason + 200) }
+
+  handler Seed phase Start {
+    spawn Enemy { Health { max: 50 } }     # entity 0 -> Spawned 100
+    spawn Enemy { Health { max: 60 } }     # entity 1 -> Spawned 101
+  }
+
+  handler Run phase Update {
+    for (h) in query [Health] { despawn self() }   # despawn 0 -> Died 200, despawn 1 -> Died 201
+    quit()
+  }
+}