Fix: Set ph_office as default map and add map download

- Changed default map from gm_construct to ph_office in start.sh
- Added ph_office to mapcycle.txt as first map
- Added download_prophunt_maps function to install.sh to automatically
  download and extract the ph_office map (Workshop ID: 188818807)
- Maps are extracted using gmad_linux for immediate use

Co-authored-by: openhands <openhands@all-hands.dev>

scripts/start.sh

@@ -9,7 +9,7 @@ SERVER_DIR="${INSTALL_DIR}/serverfiles"
 # Configuration (can be overridden with environment variables)
 SRCDS_TOKEN="${SRCDS_TOKEN:-}"
 SERVER_NAME="${SERVER_NAME:-PropHunt Server}"
-MAP="${MAP:-gm_construct}"
+MAP="${MAP:-ph_office}"
 MAX_PLAYERS="${MAX_PLAYERS:-24}"
 PORT="${PORT:-27015}"
 GAMEMODE="${GAMEMODE:-prop_hunt}"