fix(cli): 修复 type/keyboard 的 --delay 参数解析

将 --delay <ms> 从输入文本中剥离并写入 delay 字段，避免搜索词混入参数。

同时支持使用 -- 终止参数解析以输入字面量 --delay 文本，并补充回归测试与帮助文档。

README.md

@@ -143,10 +143,10 @@ agent-browser open <url>              # Navigate to URL (aliases: goto, navigate
 agent-browser click <sel>             # Click element (--new-tab to open in new tab)
 agent-browser dblclick <sel>          # Double-click element
 agent-browser focus <sel>             # Focus element
-agent-browser type <sel> <text>       # Type into element
+agent-browser type <sel> <text> [--delay <ms>]  # Type into element
 agent-browser fill <sel> <text>       # Clear and fill
 agent-browser press <key>             # Press key (Enter, Tab, Control+a) (alias: key)
-agent-browser keyboard type <text>    # Type with real keystrokes (no selector, current focus)
+agent-browser keyboard type <text> [--delay <ms>]  # Type with real keystrokes (no selector, current focus)
 agent-browser keyboard inserttext <text>  # Insert text without key events (no selector)
 agent-browser keydown <key>           # Hold key down
 agent-browser keyup <key>             # Release key