Add theme-level discovery

A synergy theme counts as explored the first time two different
fielded jokers connect it (one gives the tag, one wants it; cluster
members carry both sides, so any two qualify). Explored themes
persist in config.themes_found, badge their catalog page with
"explored!", and feed a per-tab progress line. One toast per
emplacement, with famous pairs outranking themes.

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

CLAUDE.md

@@ -86,6 +86,12 @@ Three-layer split; `JCA` is the single global namespace:
     `config.discovered` (saved immediately via `SMODS.save_mod_config`) and
     per-run in `G.GAME.jca_run_combos`. Undiscovered pairs render face-down
     with a `???` caption in the Combos tab; blurb replaces it once fielded.
+    Themes (every `theme_info` tag) persist in `config.themes_found` once
+    two DIFFERENT jokers connect the tag (giver + wanter; a joker carrying
+    both sides needs a second joker). One toast per emplacement, famous
+    pair outranking theme. Badge/progress render in `theme_tab_def`; toast
+    names come from `JCA.theme_names` (filled after THEME_TABS, used only
+    at gameplay time).
   - Post-run recap: wraps `create_UIBox_game_over`/`create_UIBox_win` and
     inserts a "Combos fielded this run" row (from `G.GAME.jca_run_combos`)
     relative to vanilla button ids (`from_game_over`; `from_game_won` or