feat: generic BIP terminal control (Simulator BIP pill) (v3.6.0)

BIP was only reachable through the SCP81 listener; cards that use TCP for
other purposes (an applet's OPEN CHANNEL, a push trigger without HTTP OTA)
now get a generic control surface, independent of SCP81.

Server:
- /api/bip/control starts a plain BIP session in three modes: sink
  (default; a local TcpDumpServer that accepts the card's channels and only
  logs conn/sink-rx/conn-close, never answering; port 0 = ephemeral, the
  bound port is reported), passthru (dial the OPEN CHANNEL destination, TCP
  client only) and redirect (fixed host:port).
- /api/bip/status returns {owner, bip, listener}; /api/bip/log and
  /api/bip/log-clear share the BIP event log with /api/scp81/log.
- The session state is shared with the SCP81 listener and only one session
  runs at a time: _bip_session_stop() stops whichever control started it
  and the control responses report it as `replaced` (both directions,
  SCP81 <-> BIP).  State renamed _SCP81_MODE/_TARGET/_LISTENER/_LINK_EVENTS
  -> _BIP_* plus _BIP_OWNER.
- TcpDumpServer logs conn-close and counts accepted connections; stop()
  joins the accept thread so the port is really free on restart.
- The new control endpoints are blocked during test-script runs.

PWA:
- New Simulator pill BIP (after TR Config): mode select with notes,
  Host/Port rules, Start/Stop with a "replaced" notice, status line (mode,
  bound address, owner, channels), a Channels box and the shared BIP log
  (reuses the SCP81 log renderer, now showing `peer`).
- The SCP81 status line marks a session owned by the BIP pill.

Help EN/RU 8.10, docs/api.md, AGENTS; CAT_TP/UDP recorded as not
implemented.

Tests: tests/test_bip.py (9) and frontend/tests/bip.test.js (6).
600 frontend / 482 Python green; version 3.6.0; sw simple-v273.

pysim_simple_server/httpota.py

@@ -423,6 +423,7 @@ class TcpDumpServer:
         self.on_log = on_log
         self.stopped = False
         self.conns = []
+        self.accepted = 0
         self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
         self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
         self.sock.bind((host, int(port)))
@@ -443,11 +444,13 @@ class TcpDumpServer:
             except OSError:
                 break
             self.conns.append(conn)
+            self.accepted += 1
             if self.on_log:
                 self.on_log('conn', peer='%s:%d' % addr[:2])
             threading.Thread(target=self._conn_loop, args=(conn, addr), daemon=True).start()
 
     def _conn_loop(self, conn, addr):
+        total = 0
         try:
             while not self.stopped:
                 conn.settimeout(0.2)
@@ -459,9 +462,12 @@ class TcpDumpServer:
                     break
                 if not data:
                     break
+                total += len(data)
                 if self.on_rx:
                     self.on_rx('%s:%d' % addr[:2], data)
         finally:
+            if self.on_log:
+                self.on_log('conn-close', peer='%s:%d' % addr[:2], bytes=total)
             try:
                 conn.close()
             except OSError:
@@ -481,3 +487,11 @@ class TcpDumpServer:
             except OSError:
                 pass
         self.conns = []
+        # Wait for the accept loop to leave accept(): a thread blocked in
+        # accept() keeps the listening socket alive for up to its poll
+        # timeout, so the port must be released before stop() returns
+        # (restarting a listener on the same port must not race).
+        try:
+            self.thread.join(timeout=2)
+        except RuntimeError:
+            pass