examples/war: polish pass + README entry + plan close-out

End-of-implementation polish for the War example after the
compiler bugs were fixed:

- Title state now calls draw_big_war_banner instead of inlining
  12 draws — same pixel output, fewer lines.
- P_WAR_BURY redraws the previous round's face-up cards while
  the noise thumps fire so the table doesn't look empty for
  24 frames between the WAR banner and the new face-ups.
- Drop draw_word_war from render.ne (orphaned by the BIG WAR
  metasprite).
- Refresh comments in background.ne (now references the real
  felt tile) and deal_state.ne (drop the stale FRAMES_DEAL_STEP
  reference now that the deal pace is hard-coded at 2 frames).
- README.md and examples/README.md gain a war row.
- PLAN.md marks every implementation step complete and records
  the design revisions made along the way.
- Refresh the war audio hash to match the new ROM (the title
  screen helper change shifts one frame of pulse-2 timing
  enough to flip the FNV-1a). The frame-180 PNG is unchanged.

https://claude.ai/code/session_0143dTgh3UeRrtfHgQwzcv5z

examples/war/render.ne

@@ -155,16 +155,6 @@ fun draw_word_wins(x: u8, y: u8) {
     draw_letter(dww_px, y, 18)  // S
 }
 
-// "WAR" — the centred flash during a tie-break.
-fun draw_word_war(x: u8, y: u8) {
-    var dwa_px: u8 = x
-    draw_letter(dwa_px, y, 22)  // W
-    dwa_px += 8
-    draw_letter(dwa_px, y, 0)   // A
-    dwa_px += 8
-    draw_letter(dwa_px, y, 17)  // R
-}
-
 // "PRESS" — used on the title screen.
 fun draw_word_press(x: u8, y: u8) {
     var dwr_px: u8 = x