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

waveshare_epd_init.py

@@ -0,0 +1,3 @@
+"""Waveshare 7.3-inch ACeP 7-Color e-Paper (F) — vendored driver."""
+from .epd7in3f import EPD
+from .epdconfig import module_exit