Move the synergy catalog from the run HUD to the pause menu

The purple Combos button lived in the run HUD button_area; move it to a
"Combos" row in the pause menu (Escape > under Settings, before
restart_button) so the play screen stays clear. Same overlay, same tabs;
Mods > Combo Advisor is unchanged.

restart_button is an id vanilla only builds during a run, so the row never
reaches the main menu. Because the pause menu builds its node list as a table
constructor with conditional entries (an unseeded run leaves a hole at the
seed row's index), find_trail/insert_node walk and shift by explicit numeric
key rather than ipairs/table.insert.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

README.md

@@ -41,8 +41,8 @@ recommends joker combos while you play:
   lineup — and, when your board is full, a "weakest combo piece" flag on
   the joker contributing least to the build, so you know the natural cut
   when something better shows up.
-- **Browse the synergy catalog** any time: a purple **Combos** button in the
-  run HUD (under Run Info / Options) opens it in an overlay, and the same
+- **Browse the synergy catalog** any time: a **Combos** row in the pause menu
+  (Escape, under Settings) opens it in an overlay, and the same
   tabs live under Mods > Combo Advisor. The *Combos* tab shows the famous
   pairs as card duos with their explanation once fielded; *Engine* /
   *Economy* / *Hands* tabs page through each synergy theme with a one-line