docs: API contract, README for the server and live mode, real-model test

docs/API.md is the full contract: run flags and environment, auth, coordinate
convention, the identity vocabulary, every REST endpoint and WebSocket message
with examples, the backpressure rule, what a client may rely on, the design
decisions with their rejected alternatives, measured performance, known
limitations, and notes for the future mobile client.

README.md (Vietnamese) now documents the client-server shape, both modes, the
flags, the API, the test commands, and the source layout. It also repairs the
PowerShell escape damage in the original file (backtick-r had become a line
break, backtick-b a backspace, backtick-a a bell), which had left the code
fences and file paths mangled.

test_real_model.py is the opt-in integration test (DORAYAKI_REAL_MODEL=1): it
guards the measured baseline (170 detections, 105 recognized on image.jpg) and
proves a pan keeps labels stable with no unexplained changes.

run_app.sh / run_app.bat pass arguments through to the server.

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

recognization/run_app.sh

@@ -3,6 +3,6 @@ echo '=========================================================='
 echo '      DORAYAKI - SMART SHELF RECOGNITION AI APP'
 echo '=========================================================='
 echo '[1/2] Installing / Checking dependencies...'
-pip install -r requirements.txt
-echo '[2/2] Starting Dorayaki Server on port 8080...'
-python3 code/app.py --port 8080
+pip install -r requirements-dev.txt
+echo '[2/2] Starting Dorayaki recognition server on port 8080...'
+python3 code/app.py --port 8080 "$@"