feat: add /ego-mgr slash command

Add /ego-mgr slash command with subcommands:
- get, set, list, delete, add-column, add-public-column, show
- Uses pcexec to call ego-mgr binary with proper env vars

Translate all Chinese text to English in responses.

Note: pcexec tool name and function names remain unchanged.

plugin/tools/pcexec.ts

@@ -201,7 +201,7 @@ async function replaceSecretMgrGets(
 }
 
 /**
- * Safe exec wrapper that handles pass_mgr get commands and sanitizes output.
+ * Safe exec wrapper that handles secret-mgr get commands and sanitizes output.
  */
 export async function pcexec(
   command: string,
@@ -297,7 +297,7 @@ export async function pcexec(
 
 /**
  * Synchronous version — password substitution is NOT supported here
- * (use async pcexec for pass_mgr integration).
+ * (use async pcexec for secret-mgr integration).
  */
 export function pcexecSync(
   command: string,