fix(docker): place MIB parser in /usr/local/bin to survive COPY backend/

The tod-mib-parser at /app/ was overwritten by COPY backend/ .
Move to /usr/local/bin/ and update config path.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/config.py

@@ -140,7 +140,7 @@ class Settings(BaseSettings):
     LICENSE_DEVICES: int = 250
 
     # MIB parser binary path (tod-mib-parser Go binary)
-    MIB_PARSER_PATH: str = "/app/tod-mib-parser"
+    MIB_PARSER_PATH: str = "/usr/local/bin/tod-mib-parser"
 
     # App settings
     APP_NAME: str = "TOD - The Other Dude"