feat(core): TCP in the simulation core

engine.ts ports Swift's "Java-compatible TCP sockets" in one piece, since
half a state machine could not be checked: server and client sockets (a
free port from Java's random numbers on their own seed), the three-way
handshake with its result (connected, invalid socket, unreachable, timed
out), segments of 1460 bytes, messages up to the push, a timeout of
3 × 2.5 s with at most three attempts, closing through every Java state
including TIME_WAIT (2.5 s), sequence numbers modulo 2^32.

Three scenarios match the Swift engine trace for trace: a LAN with data
over three segments, closing from both ends, a closed port and an
unreachable host; two networks through a router with a firewall rule,
data lost until the connection closes, and an accepted socket that does
not hold the port of its closed listener; CLOSING, reached by a lost FIN.
The engine delivers a FIN within the same close, so both ends close at
once only with packet loss; an empty message does not arrive in Swift (it
does not advance the sequence number), nor here.

Swift's four TCP engine tests are ported, with tests for stopping, a
foreign SYN+ACK at a listener and the flag names. 17 mutation probes, 16
caught; the other (delivered, not waited, not connected gives unreachable)
cannot be reached through Swift's engine, which never sends a reset and
always acknowledges correctly.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tools/swift-oracle/README.md

@@ -21,8 +21,12 @@ npm test                # vergleicht mit den geschriebenen *.swift.json
   `sat`, `speed`; UDP (seit F2): `bindUdp` (Knoten, optional Port, lokale
   Adresse, Gegenstelle; Ergebnis die Socket-ID), `sendUdp` (Socket, Text,
   optional Ziel und Port), `receiveUdp` (Socket, optional Wartezeit),
-  `closeSocket`. Das Ergebnis enthält die Sockets mit der Länge ihrer
-  Warteschlange.
+  `closeSocket`; TCP: `openTcpServer`, `openTcpClient`, `connectTcp`
+  (Ergebnis `connected`, `invalidSocket`, `unreachable`, `timedOut`),
+  `sendTcp` (mit `repeatCount` für lange Nachrichten), `receiveTcp`,
+  `acceptedTcp`, `peerTcp`, `cleanTcp`; `closeSocket` schließt auch TCP.
+  Das Ergebnis enthält die Sockets mit der Länge ihrer Warteschlange, dem
+  TCP-Zustand, dem annehmenden Socket und den Sitzungswerten.
 
 ## Korpus