Initial commit: epaper-dashboard for 7.3" ACeP 7-Color display

- dashboard.py: plugin-based renderer with 4x4 grid layout
- admin.py: web UI with layout editor + plugin configs
- layout.py: pack algorithm, item placement, grid system
- plugins/: clock, weather, system, spotify, strava, gmail, minimax, hello
- network_watchdog.py: WiFi AP/client mode management
- waveshare_epd_init.py: vendor driver stub

render_test.py

@@ -0,0 +1,8 @@
+import sys
+sys.path.insert(0, ".")
+import dashboard
+d = dashboard.Dashboard()
+img = d.render_once()
+img.save("/tmp/render_test.png")
+print("rendered:", img.size)
+print("widgets:", [(w.name if w else None) for w in d.widgets])