Start champion theme when rival dialogue ends, not at battle

The Elite Four champion script showed the rival's intro text and then
jumped straight into the battle; the wipe-time playBattle('final')
started Music_FinalBattle only when the battle began. The original
(ChampionsRoomRivalReadyToBattleScript) plays MUSIC_FINAL_BATTLE right
after the dialogue ends, before the battle.

Add a play_music Music_FinalBattle row between the intro text and the
battle, and bump the two past-the-end jump targets 25 -> 26 for the new
row count. pushBattle's wipe-time playBattle('final') no-ops on the
already-playing song, so the theme stays continuous into the fight.

Fixes #706

data/scripts/story.lua

@@ -981,10 +981,15 @@ M.VICTORY_ROAD_3F = {
 local championsRoomRivalScript = {
   { "face_player" },                                        -- 1
   { "check_flag", "EVENT_BEAT_CHAMPION_RIVAL_THIS_RUN" },   -- 2
-  { "jump_if_true", 25 },                                   -- 3  past end
+  { "jump_if_true", 26 },                                   -- 3  past end
   { "show_text", "_ChampionsRoomRivalIntroText" },          -- 4
-  { "rival_battle", "OPP_RIVAL3", 1 },                      -- 5
-  { "jump_if_false", 25 },                                  -- 6  past end
+  -- ChampionsRoomRivalReadyToBattleScript plays MUSIC_FINAL_BATTLE after
+  -- the intro text, before the battle itself (#706); pushBattle's wipe-time
+  -- playBattle("final") then no-ops on the same song, so the theme stays
+  -- continuous into the fight
+  { "play_music", "Music_FinalBattle" },                    -- 5
+  { "rival_battle", "OPP_RIVAL3", 1 },                      -- 6
+  { "jump_if_false", 26 },                                  -- 6  past end
   { "set_flag", "EVENT_BEAT_CHAMPION_RIVAL_THIS_RUN" },     -- 7
   { "set_flag", "EVENT_BEAT_CHAMPION_RIVAL" },              -- 8
   -- ChampionsRoomRivalDefeatedScript re-displays TEXT_CHAMPIONSROOM_RIVAL,