Add GPS + PPS distribution sheet (all rev-A blocks captured)

- New carrier/GPS_PPS.kicad_sch via tools/build_gps.py: J_GPS 5-pin
  (PPS + UART2 NMEA + 3V3_AUX + GND) per Pinout_BOM section 6
- PPS chain: GPS_PPS_RAW -> PESD3V3L1BA TVS -> 74LVC1G17 Schmitt
  (+3V3_AUX) -> PPS_CLEAN -> 33R series -> SYNC_OUT (CM5 pin 18 + J2.6),
  plus J_PPS1 (UWB) / J_PPS2 (scope) 2-pin taps; board is PPS sink only
- NMEA on UART2 (GPIO4/GPIO5) per correction C2; debug console keeps UART0
- Converted SYNC_OUT/GPIO4/GPIO5 local labels on CM5_GPIO to global
  (names unchanged) to reach the new sheet; root sheet-symbol needs no pins
- J_GPS pins 1/2 typed output (GPS drives PPS/TX) for driver-aware checks
- Verify: ERC 133->133 zero new; analyzer +73/-0 zero regressions; netlist
  confirms all cross-sheet nets; SPICE 24 pass / 2 benign warn / 0 fail

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

carrier/CM5_GPIO.kicad_sch

@@ -13645,7 +13645,8 @@
 		)
 		(uuid "05c1c0ae-f846-4942-b9ca-9f0f8f62492d")
 	)
-	(label "GPIO5"
+	(global_label "GPIO5"
+		(shape bidirectional)
 		(at 24.13 62.23 0)
 		(fields_autoplaced yes)
 		(effects
@@ -13964,7 +13965,8 @@
 		)
 		(uuid "2e95b89a-d151-4ceb-8ea1-75ed88f1541e")
 	)
-	(label "GPIO4"
+	(global_label "GPIO4"
+		(shape bidirectional)
 		(at 24.13 87.63 0)
 		(fields_autoplaced yes)
 		(effects
@@ -14316,7 +14318,8 @@
 		)
 		(uuid "6fa8342e-2989-40ca-b0ae-b207f17ca831")
 	)
-	(label "SYNC_OUT"
+	(global_label "SYNC_OUT"
+		(shape bidirectional)
 		(at 54.61 175.26 180)
 		(fields_autoplaced yes)
 		(effects
@@ -14459,7 +14462,8 @@
 		)
 		(uuid "88ce3174-a8b3-4149-886a-872ed4746e98")
 	)
-	(label "SYNC_OUT"
+	(global_label "SYNC_OUT"
+		(shape bidirectional)
 		(at 24.13 41.91 0)
 		(fields_autoplaced yes)
 		(effects
@@ -14525,7 +14529,8 @@
 		)
 		(uuid "91fb974e-99de-4e0c-bee5-7a6f88905951")
 	)
-	(label "GPIO5"
+	(global_label "GPIO5"
+		(shape bidirectional)
 		(at 147.32 59.69 180)
 		(fields_autoplaced yes)
 		(effects
@@ -15053,7 +15058,8 @@
 		)
 		(uuid "f6429ab2-213c-4030-a705-9f073170a98c")
 	)
-	(label "GPIO4"
+	(global_label "GPIO4"
+		(shape bidirectional)
 		(at 147.32 31.75 180)
 		(fields_autoplaced yes)
 		(effects