feat(client): save/load client UI — F5/F6 quicksave/quickload (#554)

Wire SaveGame/LoadGame player actions through the full client stack:
protocol v15 decode, InputMapper F5/F6 bindings, SimBridge wire mapping
with one-shot carry-forward, GameState save_result field, and HUD
notification via monologue display. Quit-to-menu triggers quicksave
before scene change.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/scripts/autoloads/sim_bridge.gd

@@ -289,6 +289,9 @@ func receive_bytes(bytes: PackedByteArray) -> void:
 		if old_conv_ended.size() > 0:
 			var new_conv_ended: Array = snapshot.get("conversation_ended", [])
 			snapshot["conversation_ended"] = old_conv_ended + new_conv_ended
+		# #554: Carry forward save/load result (one-shot, consumed by main.gd)
+		if snapshot.get("save_result") == null and _last_snapshot.get("save_result") != null:
+			snapshot["save_result"] = _last_snapshot["save_result"]
 	_last_snapshot = snapshot
 
 # Drain the outbound buffer. Returns raw input entries for batch encoding.
@@ -326,6 +329,10 @@ static func action_enum_to_wire(action: int) -> String:
 			return "SetFacing"  # D-054: facing octant update (no movement)
 		InputMapper.Action.TELEPORT_HUB:
 			return "TeleportToHub"  # #501: Gauntlet dev teleport (not production fast-travel)
+		InputMapper.Action.SAVE_GAME:
+			return "SaveGame"  # #554: F5 quicksave (D-085)
+		InputMapper.Action.LOAD_GAME:
+			return "LoadGame"  # #554: F6 quickload (D-085)
 		_:
 			push_warning("SimBridge: unknown action enum %s" % action)
 			return ""