README: add architecture diagrams (EN/RU)

Both READMEs gain a capture-and-analysis diagram right under the screenshot:
simtrace2-pysniff and sigrok_iso7816_stream feed the GSMTAP UDP :4729
listener, SIMtrace2 hardware can be read directly over USB, PCAP/COMPRION
traces come from files, and simtrace-analyser-server decodes/stores into
SQLite and serves the web UI.  The SVGs carry title/desc and role=img, use
only inline presentation attributes (no scripts, no external refs) and render
without clipped text; the RU text matches the EN layout.

The runtime zip includes both diagrams so the embedded READMEs keep working,
and a new drift guard checks that every image a README references is present
in the archive.  RU wording: "устанавливаемое PWA" (neuter agreement).

558 Python + 80 Node tests.

tests/test_release_zip.py

@@ -81,6 +81,21 @@ class TestReleaseZip(unittest.TestCase):
             self.assertIn('%s/frontend/%s' % (top, asset), self.names,
                           'precached %s is missing from the zip' % asset)
 
+    def test_readme_images_are_in_the_zip(self):
+        # Drift guard: the runtime tree's READMEs embed the screenshot and the
+        # architecture diagrams by relative path, so every referenced image
+        # must travel with the archive.
+        top = 'simtrace-analyser-%s' % __version__
+        for readme in ('README.md', 'README_RUS.md'):
+            text = (REPO / readme).read_text()
+            images = re.findall(r'!\[[^\]]*\]\(([^)\s]+)\)', text)
+            self.assertTrue(images, 'no images referenced by %s' % readme)
+            for image in images:
+                self.assertNotIn('://', image, image)
+                self.assertIn('%s/%s' % (top, image), self.names,
+                              '%s references %s, which is missing from the zip'
+                              % (readme, image))
+
     def test_batch_files_use_crlf(self):
         with zipfile.ZipFile(self.archive) as zf:
             bats = [n for n in self.names if n.endswith('.bat')]