feat(opencode): add language-specific coding skills

- add conventions for Bash, C#, Go, Python, and TypeScript
- add frontend guidance for HTMX, PrimeVue, and Vue
- document formatting, typing, testing, async, and framework-specific practices
- reference official documentation for framework API details

.config/opencode/skills/vue/SKILL.md

@@ -0,0 +1,25 @@
+---
+name: vue
+description: Vue 3 (Composition API, script setup, Pinia, Vue Router) conventions. Use when editing .vue files.
+---
+
+# Vue 3 Conventions
+
+Use Vue 3 with the Composition API exclusively.
+
+## Components
+- Use `<script setup lang="ts">`; avoid the Options API.
+- Type props with `defineProps<T>()` and emits with `defineEmits<T>()`.
+- Keep components focused and small; organize by feature directory.
+
+## State and routing
+- Use Pinia setup stores (`defineStore('name', () => { ... })`) for shared state.
+- Cancel superseded fetches with `AbortController`; expose loading and error state from stores.
+- Use Vue Router with route guards for protected views.
+
+## Reactivity
+- Prefer `ref` / `reactive` and `computed` over manual watchers.
+- Clean up side effects (timers, listeners, observers) in `onScopeDispose` or `onUnmounted`.
+
+## API detail
+- For exact reactivity, built-in component, and compiler behavior, fetch the Vue LLM docs index on demand: `https://vuejs.org/llms.txt`. Follow the relevant guide link for the specific API.