Add conditional boss battle teams (variant teams by condition)

Wire up the existing condition_label column on boss_pokemon to support
variant teams throughout the UI. Boss battles can now have multiple team
configurations based on conditions (e.g., starter choice in Gen 1).

- Add condition_label to BossPokemonInput schema (frontend + backend bulk import)
- Rewrite BossTeamEditor with variant tabs (Default + named conditions)
- Add variant pill selector to BossDefeatModal team preview
- Add BossTeamPreview component to RunEncounters boss cards
- Fix MissingGreenlet error in set_boss_team via session.expunge_all()
- Fix PokemonSelector state bleed between tabs via composite React key
- Add Alembic migration for condition_label column

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/BossDefeatModal.tsx

@@ -1,4 +1,4 @@
-import { type FormEvent, useState } from 'react'
+import { type FormEvent, useState, useMemo } from 'react'
 import type { BossBattle, CreateBossResultInput } from '../types/game'
 
 interface BossDefeatModalProps {
@@ -13,6 +13,26 @@ export function BossDefeatModal({ boss, onSubmit, onClose, isPending, hardcoreMo
   const [result, setResult] = useState<'won' | 'lost'>('won')
   const [attempts, setAttempts] = useState('1')
 
+  const variantLabels = useMemo(() => {
+    const labels = new Set<string>()
+    for (const bp of boss.pokemon) {
+      if (bp.conditionLabel) labels.add(bp.conditionLabel)
+    }
+    return [...labels].sort()
+  }, [boss.pokemon])
+
+  const hasVariants = variantLabels.length > 0
+  const [selectedVariant, setSelectedVariant] = useState<string | null>(
+    hasVariants ? variantLabels[0] : null,
+  )
+
+  const displayedPokemon = useMemo(() => {
+    if (!hasVariants) return boss.pokemon
+    return boss.pokemon.filter(
+      (bp) => bp.conditionLabel === selectedVariant || bp.conditionLabel === null,
+    )
+  }, [boss.pokemon, hasVariants, selectedVariant])
+
   const handleSubmit = (e: FormEvent) => {
     e.preventDefault()
     onSubmit({
@@ -34,8 +54,26 @@ export function BossDefeatModal({ boss, onSubmit, onClose, isPending, hardcoreMo
         {/* Boss team preview */}
         {boss.pokemon.length > 0 && (
           <div className="px-6 py-3 border-b border-gray-200 dark:border-gray-700">
+            {hasVariants && (
+              <div className="flex gap-1 mb-2 flex-wrap">
+                {variantLabels.map((label) => (
+                  <button
+                    key={label}
+                    type="button"
+                    onClick={() => setSelectedVariant(label)}
+                    className={`px-2 py-0.5 text-xs font-medium rounded-full transition-colors ${
+                      selectedVariant === label
+                        ? 'bg-blue-600 text-white'
+                        : 'bg-gray-100 dark:bg-gray-700 text-gray-600 dark:text-gray-300 hover:bg-gray-200 dark:hover:bg-gray-600'
+                    }`}
+                  >
+                    {label}
+                  </button>
+                ))}
+              </div>
+            )}
             <div className="flex flex-wrap gap-3">
-              {boss.pokemon
+              {[...displayedPokemon]
                 .sort((a, b) => a.order - b.order)
                 .map((bp) => (
                   <div key={bp.id} className="flex flex-col items-center">