README: correct the architecture diagram's capture paths

The diagrams conflated the SIMtrace2 hardware with the sniffer that reads it
and omitted the original Osmocom simtrace2-sniff: they showed
simtrace2-pysniff feeding the GSMTAP listener with the hardware only as its
subtitle, and a second, unexplained "SIMtrace2 hardware / direct USB" box.

The diagrams now show the device -> sniffer -> GSMTAP relationship explicitly:
SIMtrace2 hardware is read either by simtrace2-pysniff or by the original
simtrace2-sniff, and FX2 hardware by the sigrok_iso7816_stream decoder; the
sniffers/decoder stream GSMTAP-SIM to the UDP :4729 listener.  The direct USB
path is drawn separately from the device to the server and is labelled
"pysniff code in-process": --capture direct uses the bundled
simtrace2_pysniff package (DirectSniffer -> SniffSession) inside the server
process, not the simtrace2-pysniff CLI, and bypasses GSMTAP.  PCAP/COMPRION
import, SQLite and the browser UI keep their places.

The READMEs' alt text, the first-run capture-mode notes and the Usage command
comments now name the original simtrace2-sniff as a GSMTAP source and say the
direct mode runs the bundled sniffer code inside the server.

Both languages; 558 Python + 80 Node tests; runtime zip still carries both
diagrams and the README image guard passes.

README.md

@@ -13,7 +13,7 @@ GSMTAP into this analyser.
 
 ![SIMtrace Analyser UI](frontend.png)
 
-![Capture and analysis: simtrace2-pysniff (SIMtrace2 hardware) and sigrok_iso7816_stream (FX2) stream GSMTAP-SIM to the UDP :4729 listener; alternatively the server reads SIMtrace2 hardware directly over USB, and PCAP/COMPRION traces are imported from files; simtrace-analyser-server decodes and stores the traffic in SQLite and serves the web UI](architecture_en.svg)
+![Capture and analysis: SIMtrace2 hardware is read by simtrace2-pysniff or the original simtrace2-sniff, and FX2 hardware by the sigrok_iso7816_stream decoder; the sniffers and the decoder stream GSMTAP-SIM to the UDP :4729 listener. The server can also read SIMtrace2 hardware directly over USB with the bundled pysniff code in-process, and imports PCAP/COMPRION traces from files. simtrace-analyser-server decodes and stores the traffic in SQLite and serves the web UI](architecture_en.svg)
 
 ## Prerequisites
 
@@ -115,9 +115,11 @@ simtrace-analyser-server --capture gsmtap
 Open **http://127.0.0.1:8081/** in a browser.  `Ctrl+C` stops the server.
 
 - `--capture gsmtap` (default) — listen for GSMTAP-SIM on UDP 4729, e.g. from
-  `simtrace2-pysniff` or `sigrok_iso7816_stream`;
-- `--capture direct` — read SIMtrace2 hardware directly (needs PyUSB; Windows
-  also needs the driver swap, see [USB Device Access](#usb-device-access));
+  `simtrace2-pysniff`, the original `simtrace2-sniff` or
+  `sigrok_iso7816_stream`;
+- `--capture direct` — read SIMtrace2 hardware directly (the bundled sniffer
+  code runs inside the server and talks to the device over USB; needs PyUSB;
+  Windows also needs the driver swap, see [USB Device Access](#usb-device-access));
 - `--capture disabled` — only browse stored captures.
 
 The full runtime guide (server options, the UI views, the capture utility) is
@@ -133,10 +135,12 @@ bundled into the package on install) on the same origin.  Three capture
 modes:
 
 ```sh
-# Listen for GSMTAP from simtrace2-pysniff (or original simtrace2-sniff):
+# Listen for GSMTAP from simtrace2-pysniff, the original simtrace2-sniff or
+# sigrok_iso7816_stream:
 simtrace-analyser-server --capture gsmtap
 
-# Capture directly from SIMtrace2 hardware (no external tool needed):
+# Capture directly from SIMtrace2 hardware (the bundled sniffer code reads the
+# device; no external tool, no GSMTAP):
 simtrace-analyser-server --capture direct
 
 # Browse/analyse existing captures without a capture backend: