fix(docs): use namespaced /everything-claude-code:plan in README examples

When installed as a plugin, /plan triggers Claude Code's built-in plan
mode instead of the plugin's plan skill. Updated all 4 README files
(EN, zh-CN, zh-TW, ja-JP) to show the plugin-namespaced form with a
comment noting the shorter form works for manual installs.

Also fixes markdownlint MD012 violation in chief-of-staff.md (trailing
double blank line from #280 merge).

Fixes #297

README.md

@@ -145,8 +145,11 @@ For manual install instructions see the README in the `rules/` folder.
 ### Step 3: Start Using
 
 ```bash
-# Try a command
-/plan "Add user authentication"
+# Try a command (plugin install uses namespaced form)
+/everything-claude-code:plan "Add user authentication"
+
+# Manual install (Option 2) uses the shorter form:
+# /plan "Add user authentication"
 
 # Check available commands
 /plugin list everything-claude-code@everything-claude-code
@@ -624,8 +627,8 @@ Not sure where to start? Use this quick reference:
 
 | I want to... | Use this command | Agent used |
 |--------------|-----------------|------------|
-| Plan a new feature | `/plan "Add auth"` | planner |
-| Design system architecture | `/plan` + architect agent | architect |
+| Plan a new feature | `/everything-claude-code:plan "Add auth"` | planner |
+| Design system architecture | `/everything-claude-code:plan` + architect agent | architect |
 | Write code with tests first | `/tdd` | tdd-guide |
 | Review code I just wrote | `/code-review` | code-reviewer |
 | Fix a failing build | `/build-fix` | build-error-resolver |
@@ -641,7 +644,8 @@ Not sure where to start? Use this quick reference:
 
 **Starting a new feature:**
 ```
-/plan "Add user authentication with OAuth"   → planner creates implementation blueprint
+/everything-claude-code:plan "Add user authentication with OAuth"
+                                              → planner creates implementation blueprint
 /tdd                                          → tdd-guide enforces write-tests-first
 /code-review                                  → code-reviewer checks your work
 ```

README.zh-CN.md

@@ -88,8 +88,11 @@ cp -r everything-claude-code/rules/* ~/.claude/rules/
 ### 第三步：开始使用
 
 ```bash
-# 尝试一个命令
-/plan "添加用户认证"
+# 尝试一个命令（插件安装使用命名空间形式）
+/everything-claude-code:plan "添加用户认证"
+
+# 手动安装（选项2）使用简短形式：
+# /plan "添加用户认证"
 
 # 查看可用命令
 /plugin list everything-claude-code@everything-claude-code

agents/chief-of-staff.md

@@ -149,4 +149,3 @@ claude /schedule-reply "Reply to Sarah about the board meeting"
 - Gmail CLI (e.g., [gog](https://github.com/pterm/gog))
 - Node.js 18+ (for calendar-suggest.js)
 - Optional: Slack MCP server, Matrix bridge (LINE), Chrome + Playwright (Messenger)
-

docs/ja-JP/README.md

@@ -133,8 +133,11 @@ cp -r everything-claude-code/rules/golang/* ~/.claude/rules/
 ### ステップ3：使用開始
 
 ```bash
-# コマンドを試す
-/plan "ユーザー認証を追加"
+# コマンドを試す（プラグインはネームスペース形式）
+/everything-claude-code:plan "ユーザー認証を追加"
+
+# 手動インストール（オプション2）は短縮形式：
+# /plan "ユーザー認証を追加"
 
 # 利用可能なコマンドを確認
 /plugin list everything-claude-code@everything-claude-code

docs/zh-TW/README.md

@@ -88,8 +88,11 @@ cp -r everything-claude-code/rules/* ~/.claude/rules/
 ### 第三步：開始使用
 
 ```bash
-# 嘗試一個指令
-/plan "新增使用者認證"
+# 嘗試一個指令（外掛安裝使用命名空間形式）
+/everything-claude-code:plan "新增使用者認證"
+
+# 手動安裝（選項2）使用簡短形式：
+# /plan "新增使用者認證"
 
 # 查看可用指令
 /plugin list everything-claude-code@everything-claude-code