Add SMB AAPL Extensions Phase 1-6 + VFS xattr support

Phase 1: AAPL Create Context negotiation
Phase 2: AFP_AfpInfo Stream structure (Finder info + creation time)
Phase 2.5: SMB Named Stream Backend (NamedStreamPath)
Phase 2.6: Backend Named Stream Support in handlers
Phase 2.7: VFS Extended Attributes (get/set/remove/list_xattr)
Phase 4: Time Machine share config (time_machine field)
Phase 5: Server/Volume Capabilities
Phase 6: macOS Unicode mapping (private range ↔ ASCII)

Tests: 174 smb-server tests pass, 52 VFS tests pass

vendor/smb-server/src/proto/messages/create.rs

@@ -171,6 +171,7 @@ impl CreateContext {
     pub const NAME_RQLS: &'static [u8; 4] = b"RqLs"; // REQUEST_LEASE
     pub const NAME_DH2Q: &'static [u8; 4] = b"DH2Q"; // DURABLE_HANDLE_REQUEST_V2
     pub const NAME_DH2C: &'static [u8; 4] = b"DH2C"; // DURABLE_HANDLE_RECONNECT_V2
+    pub const NAME_AAPL: &'static [u8; 4] = b"AAPL"; // Apple SMB Extensions (MS-SMB2 §2.2.13.2)
 
     /// Parse a chain of create-contexts from the raw chain bytes.
     ///