feat: add CYD ThermoPro bridge firmware skeleton

Add PlatformIO project for the ESP32-2432S028R that:
- Reads ThermoPro BLE BBQ thermometers via NimBLE-Arduino
- Exposes /api/health, /api/latest, and /api/settings HTTP endpoints
- Serves a captive-portal setup UI and touch dashboard
- Persists WiFi/BLE/settings in NVS via Preferences

Builds cleanly with pio run.

cyd-bridge/README.md

@@ -76,7 +76,7 @@ Runtime settings (endpoint, token, probe names, units, polling interval) can be
 
 ## Building and flashing
 
-Requires [PlatformIO](https://platformio.org/) installed locally (not available in this cloud environment).
+Requires [PlatformIO](https://platformio.org/).
 
 ```bash
 cd cyd-bridge
@@ -102,9 +102,18 @@ Before relying on the dashboard, verify the pinout matches your exact board revi
 2. Confirm `TFT_CS`, `TFT_DC`, `TFT_RST`, `TFT_BL`, `TOUCH_CS`, and the SPI pins match the silkscreen or schematic of your ESP32-2432S028R.
 3. If the screen stays white or touch is inverted, adjust `cfg.offset_rotation` in `DisplayConfig.hpp` or `setRotation()` in `Dashboard::begin()`.
 
+## Memory usage
+
+With the default partition table the firmware uses approximately:
+
+- **RAM:** ~18 % (~58 kB of 320 kB)
+- **Flash:** ~92 % (~1.2 MB of 1.3 MB)
+
+There is enough headroom to run, but large future features (e.g. local graphing, OTA) may require switching to a larger app partition or dropping unused NimBLE options.
+
 ## Development notes
 
 - LovyanGFX driver/pin configuration lives in `src/display/DisplayConfig.hpp` and is tuned for the ESP32-2432S028R variant.
 - BLE uses `NimBLE-Arduino` to leave enough RAM for the web server and UI.
 - All user settings are stored in ESP32 NVS via `Preferences`.
-- The firmware has not yet been compiled in this environment due to missing PlatformIO tooling; it should be built locally on your development machine before flashing.
+- The firmware compiles successfully in PlatformIO; the remaining work is on-device testing and pinout verification.