rename crates/ to engrams/, bindings/ to receptors/

- crates/ → engrams/ (Rust engrams live here)
- bindings/ → receptors/ (cross-language access points into the graph)
- Cargo.toml workspace paths updated

engrams/engram-server/src/state.rs

@@ -0,0 +1,19 @@
+/// Shared application state for all request handlers.
+use engram_core::EngramDb;
+use engram_projection::registry::ProjectionRegistry;
+use engram_sync::SyncEngine;
+use engram_tx::TransactionEngine;
+use std::sync::{Arc, Mutex};
+
+pub struct AppState {
+    /// Local database — uses std::sync::Mutex (sync ops only, fast)
+    pub db: Arc<Mutex<EngramDb>>,
+    /// Sync engine — uses tokio::sync::Mutex so it can be held across .await
+    pub sync_engine: Arc<tokio::sync::Mutex<SyncEngine>>,
+    /// API key used to authenticate incoming sync requests
+    pub api_key: String,
+    /// Projection registry — named schema views over the activation surface
+    pub projection_registry: Arc<Mutex<ProjectionRegistry>>,
+    /// Transaction engine — append-only command log with rollback support
+    pub tx_engine: Arc<Mutex<TransactionEngine>>,
+}