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/prop_events.ludic

@@ -0,0 +1,26 @@
+# prop_events.ludic — EV1 for properties: @Public promotes the structural
+# attach/detach hooks to public events, so a mod sees a property appear or vanish
+# on a live entity (the same shape works for @OnEnable/@OnDisable → enable/disable
+# events). This extends the public-event surface past models to properties —
+# "events for properties, models, scenes, layers" in the architecture.
+#
+# Running it prints:  300 400
+program PropEvents {
+  property Tag    { v: int = 0 }
+  property Shield { amount: int = 0 }
+  model Unit { Tag }
+
+  @Public @OnAttach(Shield) handler Up   { }   # -> prop_Shield_attach
+  @Public @OnDetach(Shield) handler Down { }   # -> prop_Shield_detach
+
+  @On(prop_Shield_attach) handler Gained { print(entity + 300) }   # entity 0 -> 300
+  @On(prop_Shield_detach) handler Lost   { print(entity + 400) }   # entity 0 -> 400
+
+  handler Seed phase Start { spawn Unit { Tag { v: 1 } } }         # entity 0
+
+  handler Run phase Render {
+    for (u) in query [Unit]   { attach Shield on self() { amount: 5 } }   # -> prop_Shield_attach -> 300
+    for (s) in query [Shield] { detach Shield on self() }                # -> prop_Shield_detach -> 400
+    quit()
+  }
+}