Replace playstyle rules with free-text custom rules markdown field

Remove hardcoreMode, setModeOnly, and bossTeamMatch toggles which had
no mechanical impact on the tracker. Replace them with a customRules
markdown field so users can document their own rules (especially useful
for genlockes). Add react-markdown + remark-gfm for rendering and
@tailwindcss/typography for prose styling. The custom rules display is
collapsible and hidden by default.

Also simplifies the BossDefeatModal by removing the Lost result and
attempts counter, and always shows boss team size in the level cap bar.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.beans/nuzlocke-tracker-wb85--replace-playstyle-rules-with-custom-rules-markdown.md

@@ -0,0 +1,11 @@
+---
+# nuzlocke-tracker-wb85
+title: Replace playstyle rules with custom rules markdown field
+status: completed
+type: feature
+priority: normal
+created_at: 2026-03-20T13:48:50Z
+updated_at: 2026-03-20T13:53:08Z
+---
+
+Remove hardcoreMode, setModeOnly, bossTeamMatch playstyle rules. Add a free-text markdown customRules field so users can track their own rules (especially useful for genlockes). Also: remove 'Lost' result and attempts from BossDefeatModal, always show boss team size.