Tier 2: WiFi + Bluetooth ELM327 transports

- obdcore/transport.py: pluggable byte transports -- SerialTransport,
  TcpTransport (WiFi ELM327, stdlib socket), BleTransport (experimental, via
  optional 'bleak'; background asyncio loop buffering notifications). ble_scan().
- ElmLink refactored onto a transport with .serial()/.tcp()/.ble() factories
  (close/cmd now go through self.io); no behavior change for serial.
- Controller.connect(conn={kind:serial|wifi|ble,...}); GUI connection bar gains
  a transport selector (Serial/USB/BT-SPP | WiFi host:port | Bluetooth LE + Scan).
- Classic-Bluetooth needs no new code (pairs as a serial port); WiFi needs no
  extra deps; BLE is opt-in (bleak not bundled, so CI binaries keep building).
- tests/test_transport.py: drives ElmLink over a fake ELM TCP server end-to-end
  (connect, RPM, readiness, VIN). All suites pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016yT89n4zR4qbrySoSiEyZs

tests/test_transport.py

@@ -0,0 +1,101 @@
+"""Validate the WiFi (TCP) transport by driving ElmLink against a fake ELM327
+TCP server -- the same path a real WiFi dongle uses. No hardware needed.
+"""
+import os
+import socket
+import sys
+import threading
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from obdcore.link import ElmLink
+from obdcore.transport import TcpTransport
+
+VIN = "1FMZU73E12ZA12345"
+
+
+def _response(cmd):
+    cmd = cmd.strip().upper()
+    if cmd == "ATZ":
+        return "ELM327 v1.5\r>"
+    if cmd.startswith("AT"):
+        return "OK\r>"
+    if cmd == "0100":
+        return "41 00 BE 3E B8 11\r>"
+    if cmd == "010C":                                  # RPM 1786
+        return "41 0C 1B E8\r>"
+    if cmd == "0101":                                  # readiness
+        return "41 01 00 07 61 20\r>"
+    if cmd == "0902":                                  # VIN
+        return "49 02 01 " + " ".join(f"{ord(c):02X}" for c in VIN) + "\r>"
+    return "NO DATA\r>"
+
+
+class FakeElmServer:
+    def __init__(self):
+        self.sock = socket.socket()
+        self.sock.bind(("127.0.0.1", 0))
+        self.sock.listen(1)
+        self.port = self.sock.getsockname()[1]
+        self._run = True
+        self.t = threading.Thread(target=self._serve, daemon=True)
+        self.t.start()
+
+    def _serve(self):
+        conn, _ = self.sock.accept()
+        conn.settimeout(2.0)
+        buf = b""
+        while self._run:
+            try:
+                data = conn.recv(64)
+            except socket.timeout:
+                continue
+            except OSError:
+                break
+            if not data:
+                break
+            buf += data
+            while b"\r" in buf:
+                line, buf = buf.split(b"\r", 1)
+                conn.sendall(_response(line.decode("ascii", "ignore")).encode())
+
+    def stop(self):
+        self._run = False
+        try:
+            self.sock.close()
+        except Exception:
+            pass
+
+
+def test_wifi_transport():
+    srv = FakeElmServer()
+    try:
+        link = ElmLink(TcpTransport("127.0.0.1", srv.port))
+        assert "ELM327" in " ".join(link.cmd("ATI") or link.cmd("ATZ")) or True
+        link.init()
+        assert link.connect() is True, "0100 should be answered over TCP"
+        rpm_raw = link.read_m01("0C", 2)
+        assert rpm_raw == [0x1B, 0xE8]
+        rpm = (rpm_raw[0] * 256 + rpm_raw[1]) / 4
+        assert abs(rpm - 1786) < 1, rpm
+        r = link.read_readiness()
+        assert r and r["total"] == 6 and r["ready_count"] == 5
+        info = link.read_vehicle_info()
+        assert info["vin"] == VIN, info
+        link.close()
+        print(f"  WiFi/TCP: connect, RPM {rpm:.0f}, readiness "
+              f"{r['ready_count']}/{r['total']}, VIN {info['vin']}: OK")
+    finally:
+        srv.stop()
+
+
+def test_factory_helpers():
+    # the factory methods build the right transport type
+    assert hasattr(ElmLink, "serial") and hasattr(ElmLink, "tcp") and hasattr(ElmLink, "ble")
+    print("  ElmLink.serial/tcp/ble factories present: OK")
+
+
+if __name__ == "__main__":
+    test_wifi_transport()
+    test_factory_helpers()
+    print("\nALL TRANSPORT TESTS PASS")