feat(simulation): Sprint 19 — 7 server systems

Protocol handshake (#555): HandshakeMessage as first IPC frame,
HandshakeState resource, forward-compatible input handling.

State serialization (#96): serialize_npc_to_frozen/deserialize with
full D-024 axis coverage (10 new optional fields on NpcSaveState).

Scope tags (#98): ScopeTagKind enum, ScopePinned marker, automatic
assignment from KnowledgeGraph and RelationshipGraph.

Timestamp eviction (#97): LastInteractionTick, SimSpacePressure,
BinaryHeap LRU eviction respecting ScopePinned entities.

Save/load (#553): save_to_file/load_from_file via MessagePack,
SaveGame/LoadGame IPC commands, SaveLoadResultWire on snapshot.

Test infrastructure (#200): Layer 3 integration test entry point,
three-layer architecture documented per D-030.

Information boundary tests (#272): 4 negative tests proving no
passive KG leakage, LOS fog holds, tier boundary holds, save
isolation per NPC.

1063 tests passing, 0 failures.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/Cargo.toml

@@ -24,3 +24,13 @@ gauntlet = []
 
 [dev-dependencies]
 serde_json = "1"
+
+# ---------------------------------------------------------------------------
+# Explicit test target for the Layer 3 integration module (D-030, ticket #200).
+# tests/integration/mod.rs cannot be auto-discovered by cargo (only top-level
+# *.rs files in tests/ are auto-discovered). This declaration makes it a named
+# test binary: `cargo test --test integration_layer3`.
+# ---------------------------------------------------------------------------
+[[test]]
+name = "integration_layer3"
+path = "tests/integration/mod.rs"