feat: Add Kits + FurnaceSplitter plugin config modules

DB migrations 016 (kits_configs) and 019 (furnacesplitter_configs) applied.
Backend: NestJS modules with CRUD, apply-to-server, import-from-server.
Frontend: Pinia stores, Vue views with config editor, router + nav wiring.
Kits view: 3-tab editor (list/editor/settings), kit items with shortname/amount/skinId/container.
FurnaceSplitter view: per-furnace toggles, split count, fuel multiplier settings.

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

frontend/src/stores/furnacesplitter.ts

@@ -0,0 +1,145 @@
+import { defineStore } from 'pinia'
+import { ref } from 'vue'
+import { useApi } from '@/composables/useApi'
+import { useToastStore } from '@/stores/toast'
+import type { FurnaceSplitterConfigSummary, FurnaceSplitterConfigFull, FurnaceSplitterApplyResult } from '@/types'
+
+export const useFurnaceSplitterStore = defineStore('furnacesplitter', () => {
+  const configs = ref<FurnaceSplitterConfigSummary[]>([])
+  const currentConfig = ref<FurnaceSplitterConfigFull | null>(null)
+  const isLoading = ref(false)
+  const isSaving = ref(false)
+  const isApplying = ref(false)
+  const isDirty = ref(false)
+  const api = useApi()
+  const toast = useToastStore()
+
+  async function fetchConfigs() {
+    isLoading.value = true
+    try {
+      const res = await api.get<{ configs: FurnaceSplitterConfigSummary[] }>('/furnacesplitter/configs')
+      configs.value = res.configs
+    } catch (err) {
+      toast.error((err as Error).message)
+    } finally {
+      isLoading.value = false
+    }
+  }
+
+  async function loadConfig(id: string) {
+    isLoading.value = true
+    try {
+      const res = await api.get<{ config: FurnaceSplitterConfigFull }>(`/furnacesplitter/configs/${id}`)
+      currentConfig.value = res.config
+      isDirty.value = false
+    } catch (err) {
+      toast.error((err as Error).message)
+    } finally {
+      isLoading.value = false
+    }
+  }
+
+  async function createConfig(name: string, description?: string) {
+    try {
+      const res = await api.post<{ config: FurnaceSplitterConfigFull }>('/furnacesplitter/configs', {
+        config_name: name,
+        description,
+      })
+      await fetchConfigs()
+      currentConfig.value = res.config
+      isDirty.value = false
+      toast.success(`Config "${name}" created`)
+      return res.config
+    } catch (err) {
+      toast.error((err as Error).message)
+      return null
+    }
+  }
+
+  async function saveCurrentConfig() {
+    if (!currentConfig.value) return
+    isSaving.value = true
+    try {
+      await api.put(`/furnacesplitter/configs/${currentConfig.value.id}`, {
+        config_name: currentConfig.value.config_name,
+        description: currentConfig.value.description,
+        config_data: currentConfig.value.config_data,
+      })
+      isDirty.value = false
+      await fetchConfigs()
+      toast.success('Config saved')
+    } catch (err) {
+      toast.error((err as Error).message)
+    } finally {
+      isSaving.value = false
+    }
+  }
+
+  async function deleteConfig(id: string) {
+    try {
+      await api.del(`/furnacesplitter/configs/${id}`)
+      if (currentConfig.value?.id === id) {
+        currentConfig.value = null
+      }
+      await fetchConfigs()
+      toast.success('Config deleted')
+    } catch (err) {
+      toast.error((err as Error).message)
+    }
+  }
+
+  async function applyToServer(id: string) {
+    isApplying.value = true
+    try {
+      const res = await api.post<FurnaceSplitterApplyResult>(`/furnacesplitter/configs/${id}/apply`)
+      await fetchConfigs()
+      toast.success(res.message)
+      return res
+    } catch (err) {
+      toast.error((err as Error).message)
+      return null
+    } finally {
+      isApplying.value = false
+    }
+  }
+
+  async function importFromServer(configName: string) {
+    isLoading.value = true
+    try {
+      const res = await api.post<{ config: FurnaceSplitterConfigFull }>('/furnacesplitter/import-from-server', {
+        config_name: configName,
+      })
+      await fetchConfigs()
+      currentConfig.value = res.config
+      isDirty.value = false
+      toast.success(`Config imported from server as "${configName}"`)
+      return res.config
+    } catch (err) {
+      toast.error((err as Error).message)
+      return null
+    } finally {
+      isLoading.value = false
+    }
+  }
+
+  function markDirty() {
+    isDirty.value = true
+  }
+
+  return {
+    configs,
+    currentConfig,
+    isLoading,
+    isSaving,
+    isApplying,
+    isDirty,
+    fetchConfigs,
+    loadConfig,
+    createConfig,
+    saveCurrentConfig,
+    deleteConfig,
+    applyToServer,
+    importFromServer,
+    markDirty,
+  }
+})