docs(plugin): improve skill descriptions and add auto-update instructions (#602)

Signed-off-by: JasonXuDeveloper - 傑 <jason@xgamedev.net>

Author: JasonXuDeveloper

.claude-plugin/README.md

@@ -5,14 +5,23 @@ AI-powered development guide for JEngine Unity framework.
 ## Installation
 
 ```bash
-# Add JEngine marketplace (one-time, enables auto-updates)
+# Add JEngine marketplace (one-time)
 claude plugin marketplace add JasonXuDeveloper/JEngine
 
 # Install plugin
 claude plugin install jengine@jengine-marketplace
 ```
 
-Plugin updates automatically when Claude Code starts.
+## Enable Auto-Updates (Recommended)
+
+Third-party plugins require manual opt-in for auto-updates:
+
+1. Run `/plugin` in Claude Code
+2. Go to **Marketplaces** tab
+3. Select **jengine-marketplace**
+4. Toggle **Enable auto-update**
+
+Once enabled, plugin updates automatically when Claude Code starts.
 
 ## Features
 

.claude-plugin/skills/editor-ui/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: editor-ui
-description: JEngine Editor UI components. Triggers on: custom inspector, editor window, Unity editor UI, UIElements, VisualElement, progress bar, status bar, breadcrumb, form field
+description: JEngine Editor UI component library with theming. Triggers on: custom inspector, editor window, Unity editor UI, UIElements, VisualElement, JButton, JStack, JCard, JTextField, JDropdown, design tokens, dark theme, light theme, editor styling, themed button, form layout, progress bar, status bar, toggle button, button group
 ---
 
 # JEngine Editor UI Components

.claude-plugin/skills/jaction/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: jaction
-description: JAction chainable task system. Triggers on: sequential tasks, delays, timers, repeat loops, WaitUntil, async workflows, zero-allocation async
+description: JAction fluent chainable task system for Unity. Triggers on: sequential tasks, delay, timer, repeat loop, WaitUntil, WaitWhile, async workflow, zero-allocation async, coroutine alternative, scheduled action, timed event, polling condition, action sequence, ExecuteAsync
 ---
 
 # JAction - Chainable Task Execution

.claude-plugin/skills/jobjectpool/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: jobjectpool
-description: JObjectPool thread-safe pooling. Triggers on: object pool, GC optimization, reusable instances, bullet pool, spawn pool, reduce garbage collection
+description: JObjectPool thread-safe object pooling for Unity. Triggers on: object pool, GC optimization, reusable instances, bullet pool, enemy pool, effect pool, spawn pool, reduce garbage collection, memory optimization, pool prewarm, Rent Return pattern, lock-free pool
 ---
 
 # JObjectPool - Thread-Safe Object Pooling

.claude-plugin/skills/messagebox/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: messagebox
-description: MessageBox async dialogs. Triggers on: confirmation dialog, modal, prompt, alert, user confirmation, yes/no dialog
+description: MessageBox async modal dialogs for Unity with UniTask. Triggers on: confirmation dialog, modal popup, prompt, alert, user confirmation, yes/no dialog, OK/Cancel, async dialog, await user input, delete confirmation, save confirmation
 ---
 
 # MessageBox - Async Modal Dialogs