devex: fix claude.md (#5439)

* feat: start on agents.md/claude.md

* feat: set up

* feat: api-client claude + skills

* feat: apps/frontend

* feat: skills list

* fix: lint issues

.claude/skills/cross-platform-pages/SKILL.md

@@ -0,0 +1,144 @@
+# Cross-Platform Page System
+
+When a page needs to exist in both the Modrinth App (`apps/app-frontend`) and the Modrinth Website (`apps/frontend`), use the cross-platform page system.
+
+## How It Works
+
+1. **Pages live as Vue SFCs in `packages/ui`** — either in `src/pages/` or `src/layout/` (if `src/pages/` doesn't exist, it's been renamed to `src/layout/`).
+2. **Platform-dependent data flows via DI** — the app uses Tauri `invoke` commands, the website uses `api-client` or the legacy `useBaseFetch` composable. The shared page never knows which. See the `dependency-injection` skill for full DI docs.
+3. **Non-platform-dependent data flows via props** — if data doesn't change based on _how_ it's fetched, just pass it as a prop.
+
+## Example: Content Page
+
+`ContentPageLayout` demonstrates the full pattern.
+
+### 1. Define a DI contract in `packages/ui/src/providers/`
+
+The provider interface abstracts all platform-specific operations:
+
+```ts
+// packages/ui/src/providers/content-manager.ts
+export interface ContentManagerContext {
+	items: Ref<ContentItem[]>
+	loading: Ref<boolean>
+	error: Ref<Error | null>
+	contentTypeLabel: Ref<string>
+
+	// These are the platform-abstracted operations:
+	// App uses invoke(), website uses api-client
+	toggleEnabled: (item: ContentItem) => Promise<void>
+	deleteItem: (item: ContentItem) => Promise<void>
+	refresh: () => Promise<void>
+	browse: () => void
+	uploadFiles: () => void
+
+	// Optional capabilities — not every platform supports everything
+	hasUpdateSupport: boolean
+	updateItem?: (item: ContentItem) => Promise<void>
+	bulkUpdateItem?: (items: ContentItem[]) => Promise<void>
+
+	mapToTableItem: (item: ContentItem) => ContentCardTableItem
+}
+
+export const [injectContentManager, provideContentManager] =
+	createContext<ContentManagerContext>('ContentManager')
+```
+
+### 2. Build the shared page in `packages/ui`
+
+The page component injects the context and handles all UI logic (search, filtering, selection, bulk operations, empty states, modals) without knowing the platform:
+
+```vue
+<!-- packages/ui/src/components/instances/ContentPageLayout.vue -->
+<script setup lang="ts">
+import { injectContentManager } from '../../providers/content-manager'
+
+const { items, loading, toggleEnabled, deleteItem, refresh, mapToTableItem } =
+	injectContentManager()
+
+// All UI logic lives here — search, filters, sort, bulk ops, etc.
+</script>
+
+<template>
+	<ContentCardTable :items="filteredItems" />
+</template>
+```
+
+### 3. Each platform provides its implementation
+
+**Website (Nuxt)** — uses `api-client` or `useBaseFetch`:
+
+```vue
+<!-- apps/frontend/src/pages/hosting/manage/[id]/content.vue -->
+<script setup lang="ts">
+import { provideContentManager, ContentPageLayout } from '@modrinth/ui'
+const { labrinth } = injectModrinthClient()
+
+const { data: items } = useQuery({
+	queryKey: ['content', serverId],
+	queryFn: () => labrinth.servers_v0.getAddons(serverId),
+})
+
+provideContentManager({
+	items: computed(() => items.value?.map(addonToContentItem) ?? []),
+	deleteItem: async (item) => {
+		await labrinth.servers_v0.deleteAddon(serverId, item.id)
+	},
+	// ... rest of the contract
+})
+</script>
+
+<template>
+	<ContentPageLayout />
+</template>
+```
+
+**App (Tauri)** — uses `invoke`:
+
+```vue
+<!-- apps/app-frontend/src/pages/instance/Content.vue -->
+<script setup lang="ts">
+import { provideContentManager, ContentPageLayout } from '@modrinth/ui'
+import { invoke } from '@tauri-apps/api/core'
+
+const items = ref<ContentItem[]>([])
+await invoke('get_instance_content', { instanceId }).then(/* map to ContentItem[] */)
+
+provideContentManager({
+	items,
+	deleteItem: async (item) => {
+		await invoke('delete_content', { instanceId, path: item.file_path })
+	},
+	// ... rest of the contract
+})
+</script>
+
+<template>
+	<ContentPageLayout />
+</template>
+```
+
+## When to Use Props vs DI
+
+| Use       | When                                                                                                     |
+| --------- | -------------------------------------------------------------------------------------------------------- |
+| **DI**    | The data depends on _how_ it's fetched (different per platform) — API calls, file operations, navigation |
+| **Props** | The data is the same regardless of platform — configuration flags, display options                       |
+
+## Composables for Shared Logic
+
+Extract reusable stateful logic into composables in `packages/ui/src/composables/`. The shared page orchestrates them internally:
+
+- Search (Fuse.js fuzzy search over items)
+- Filtering (dynamic filter pills)
+- Selection (multi-select with bulk operations)
+- Bulk operations (sequential execution with progress tracking)
+
+## Key Files
+
+- `packages/ui/src/pages/` (or `src/layout/`) — shared page components
+- `packages/ui/src/providers/` — DI contracts
+- `packages/ui/src/composables/` — shared stateful logic
+- `apps/frontend/src/app.vue` — website root provider setup
+- `apps/app-frontend/src/App.vue` — app root provider setup
+- `apps/app-frontend/src/routes.js` — app route definitions