refactor(printer): remove BLE backend and dependencies

README.md

@@ -2,16 +2,13 @@
 
 ESP32-S3 works as a Wi-Fi REST controller and replaces Android App logic:
 - REST client -> ESP32-S3 (`esp_http_server`)
-- ESP32-S3 -> BLE printer (`TQPrinter` / `lyfPrinter`, `FFF2` write / `FFF1` notify)
-- Command compatibility:
-  - Print path: `0x00~0x07`
-  - OTA path: `0xA0~0xA4`
+- ESP32-S3 -> onboard direct thermal printer driver
 
 ## Features
 
 - Wi-Fi STA-only mode (configured SSID/password; no SoftAP fallback)
 - Built-in minimal web UI at `/` for voice tap2talk
-- BLE central client auto-scan/connect to printer name
+- Direct thermal printer control with sensor precheck
 - Async print queue with jobs (`queued/running/success/failed/canceled`)
 - Printer precheck (paper / battery / temperature)
 - Built-in UTF-8 text rendering with Chinese support (GB2312 character set, 16x16 bitmap)
@@ -19,12 +16,6 @@ ESP32-S3 works as a Wi-Fi REST controller and replaces Android App logic:
   - ES8311 microphone/speaker via `esp_codec_dev`
   - raw-opus uplink/downlink via `esp_audio_codec`
   - WebSocket transport via `esp_websocket_client`
-- Android-compatible print flow:
-  - `0x00` power on
-  - `0x03` set print param
-  - `0x04` chunked raster send + ACK
-  - `0x00` power off
-  - `0x02` feed paper
 - REST APIs:
   - Root:
     - `GET /`
@@ -148,17 +139,9 @@ curl http://<esp-ip>/v1/health
 ```bash
 curl -X POST http://<esp-ip>/v1/printer/connect \
   -H 'Content-Type: application/json' \
-  -d '{"name":"TQPrinter","timeout_ms":15000}'
-# Legacy device name is also supported:
-# -d '{"name":"lyfPrinter","timeout_ms":15000}'
-```
-
-Auto-match a compatible printer (by BLE service `0xFFF0`):
-
-```bash
-curl -X POST http://<esp-ip>/v1/printer/connect \
-  -H 'Content-Type: application/json' \
-  -d '{"name":"*","timeout_ms":20000}'
+  -d '{"timeout_ms":15000}'
+# Optional explicit backend field:
+# -d '{"backend":"direct","timeout_ms":15000}'
 ```
 
 ### Raster print
@@ -255,7 +238,6 @@ curl -X POST http://<esp-ip>/v1/voice/session/stop
 
 ## Notes
 
-- BLE side is central/client role, not printer peripheral role.
 - `base64_msb_1bpp` uses Android-compatible bit order (MSB first).
 - `/v1/print/image` supports two modes: JSON prompt generation (DashScope Z-Image) and raw `image/png` upload (no base64 wrapper).
 - `/v1/print/text` supports UTF-8 Chinese via embedded 16x16 GB2312 glyphs.