Add JSDoc to userService

[github-actions]

Add concise JSDoc comments to the user service functions so future contributors can understand the intended behavior.

Acceptance Criteria

• Keep the pull request focused.
• Include a short summary of the change.
• Link this issue in the pull request description.

/bounty $50

[xevrion-v2]

/bounty $50

[algora-pbc]

💎 $50 bounty • xevrion-v2

Steps to solve:

1. Start working: Comment /attempt #1 with your implementation plan
2. Submit work: Create a pull request including /claim #1 in the PR body to claim the bounty
3. Receive payment: 100% of the bounty is received 2-5 days post-reward. Make sure you are eligible for payouts

❗ Important guidelines:

• To claim a bounty, you need to provide a short demo video of your changes in your pull request
• If anything is unclear, ask for clarification before starting as this will help avoid potential rework
• Low quality AI PRs will not receive review and will be closed
• Do not ask to be assigned unless you've contributed before

Thank you for contributing to xevrion-v2/agent-playground!

Attempt	Started (UTC)	Solution	Actions
🟢 @DENGXUELIN	Jun 03, 2026, 07:22:00 AM	#66	Reward
🟢 @sosal123tyu1	Jun 03, 2026, 10:21:53 AM	#107	Reward
🟢 @KHHH2312	Jun 03, 2026, 11:44:36 AM	#55	Reward
🟢 @deahragz	Jun 03, 2026, 04:00:44 PM	#151	Reward
🟢 @Vincent1-p	Jun 03, 2026, 11:30:59 PM	#232	Reward
🟢 @AxisIV	Jun 04, 2026, 12:39:27 AM	#239	Reward
🟢 @bozicovichsantiago20-oss	Jun 04, 2026, 12:17:39 AM	#237	Reward
🟢 @tudorian95	Jun 04, 2026, 10:12:20 AM	#401	Reward
🟢 @xi140611-tech	Jun 04, 2026, 12:00:49 PM	#448	Reward
🟢 @alejandrorivas-pixel	Jun 05, 2026, 11:28:36 PM	#812	Reward
🟢 @catcherintheroad-hub	Jun 06, 2026, 01:35:19 AM	#856	Reward
🟢 @elianguitarra	Jun 06, 2026, 03:07:32 AM	#871	Reward
🟢 @martinezriverajosem1n-source	Jun 06, 2026, 01:32:22 PM	#956	Reward
🟢 @modelsbridgeaicom-ship-it	Jun 06, 2026, 02:46:07 PM	#963	Reward
🟢 @MrDiscipline	Jun 06, 2026, 05:44:28 PM	#991	Reward
🟢 @MAUROCERON	Jun 06, 2026, 08:56:37 PM	#997	Reward
🟢 @lin-zhiying	Jun 07, 2026, 03:01:41 AM	#1026	Reward
🟢 @qingluan-bot	Jun 07, 2026, 04:42:34 AM	#1044	Reward
🟢 @Vamshidhar-0814	Jun 07, 2026, 08:05:25 AM	#1059	Reward
🟢 @cuph7022	Jun 07, 2026, 10:48:21 AM	#1074	Reward
🟢 @szx19970521	Jun 07, 2026, 11:26:05 AM	#1079	Reward
🟢 @yanziwei	Jun 07, 2026, 05:47:39 PM	#1116	Reward
🟢 @michaelapollopimentel-svg	Jun 07, 2026, 06:58:05 PM	#1129	Reward
🟢 @awyoo	Jun 07, 2026, 07:46:44 PM	#1136	Reward
🟢 @automatizacionahedo-sudo	Jun 07, 2026, 08:46:53 PM	#1144	Reward
🟢 @cendd	Jun 08, 2026, 08:53:20 AM	#1229	Reward
🟢 @JamesJi79	Jun 08, 2026, 02:50:12 PM	WIP

[KHHH2312]

I am working on this