v1.9.1: PNG Material Design icons — 28 icons, dark/light theme, HiDPI, graceful Unicode fallback

- 56 PNG icons (28 unique × 2 color variants) from Material Design Icons (round style, 96×96px)
- core/icons.py: ctk_icon(), make_icon_button(), reconfigure_icon_button() with CTkImage cache
- Updated 15 GUI files: app.py, sidebar.py, server_dialog.py, all tabs
- build.py: auto-include assets/icons/ in PyInstaller bundle, patch rollover at 99→minor+1
- tools/download_icons.py: icon download script
- Automatic dark↔light theme switching via CTkImage dual-image support

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tools/download_icons.py

@@ -0,0 +1,64 @@
+#!/usr/bin/env python3
+"""Download Material Design Icons PNG from GitHub.
+
+Source: github.com/material-icons/material-icons-png (Apache 2.0)
+Style: round-4x (96x96 px) — enough for 4x HiDPI
+"""
+import os
+import urllib.request
+import time
+
+PROJECT_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+BASE_URL = "https://raw.githubusercontent.com/material-icons/material-icons-png/master/png"
+
+ICONS = [
+    "add", "arrow_back", "arrow_upward", "backspace", "check", "close",
+    "code", "computer", "content_copy", "dashboard", "delete", "edit",
+    "file_upload", "folder", "folder_open", "info",
+    "language", "lock", "play_arrow", "refresh", "save", "search",
+    "settings", "storage", "trending_up", "visibility", "vpn_key",
+]
+
+# Icons with different names on GitHub vs local filename
+ICON_RENAMES = {
+    "get_app": "file_download",  # Material "get_app" = download icon
+}
+
+# GitHub color dir → local theme dir
+VARIANTS = {"white": "dark", "black": "light"}
+
+
+def download():
+    done = 0
+    errors = 0
+    all_icons = [(name, name) for name in ICONS]
+    all_icons += [(gh_name, local_name) for gh_name, local_name in ICON_RENAMES.items()]
+    total = len(all_icons) * len(VARIANTS)
+
+    for gh_color, local_dir in VARIANTS.items():
+        out_dir = os.path.join(PROJECT_DIR, "assets", "icons", local_dir)
+        os.makedirs(out_dir, exist_ok=True)
+        for gh_name, local_name in all_icons:
+            done += 1
+            dst = os.path.join(out_dir, f"{local_name}.png")
+            if os.path.exists(dst):
+                print(f"  [{done}/{total}] SKIP {local_dir}/{local_name}.png")
+                continue
+            url = f"{BASE_URL}/{gh_color}/{gh_name}/round-4x.png"
+            print(f"  [{done}/{total}] GET  {local_dir}/{local_name}.png ...", end=" ")
+            try:
+                urllib.request.urlretrieve(url, dst)
+                size_kb = os.path.getsize(dst) / 1024
+                print(f"OK ({size_kb:.1f} KB)")
+            except Exception as e:
+                print(f"FAIL: {e}")
+                errors += 1
+            time.sleep(0.1)
+
+    print(f"\nDone: {total - errors}/{total} icons downloaded")
+    if errors:
+        print(f"  {errors} errors — re-run to retry")
+
+
+if __name__ == "__main__":
+    download()