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

config.example.json

@@ -0,0 +1,10 @@
+{
+  "version": 1,
+  "refresh_interval_s": 180,
+  "slots": [
+    {"plugin": "clock",   "config": {}},
+    {"plugin": "weather", "config": {"location": "52.52,13.41", "show_uv": true, "show_forecast_hours": 4}},
+    {"plugin": "system",  "config": {"show_uptime": true, "show_load": true}},
+    {"plugin": "hello",   "config": {"text": "Edit me in the web UI!", "color": "accent", "size": 40}}
+  ]
+}