Enable GPS time sync for ThinkNode M1 repeater builds

Add PERSISTANT_GPS and ENV_SKIP_GPS_DETECT flags to the ThinkNode M1
repeater build so the GPS module is active from boot and automatically
syncs the RTC clock.

Without these flags, GPS detection fails on cold-starting GPS modules
that need more than 1 second to begin outputting NMEA data, causing
gps_detected=false and hiding all GPS CLI commands. The existing
MicroNMEALocationProvider already handles initial sync after fix
acquisition and periodic re-sync every 30 minutes - these flags just
ensure it is enabled.

Relates to #1426

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

variants/thinknode_m1/platformio.ini

@@ -43,6 +43,8 @@ build_flags =
   -D ADVERT_LON=0.0
   -D ADMIN_PASSWORD='"password"'
   -D MAX_NEIGHBOURS=50
+  -D PERSISTANT_GPS=1
+  -D ENV_SKIP_GPS_DETECT=1
 ;  -D MESH_PACKET_LOGGING=1
 ;  -D MESH_DEBUG=1
 build_src_filter = ${ThinkNode_M1.build_src_filter}