Log error message and stack trace in SocialMediaService catch handlers

[TaprootFreak]

Summary

• Passing an Error object as the second argument to NestJS's Logger.error() makes it interpret the error as trace: string. The logger then calls toString(), which only yields "Error: <msg>" and drops the actual stack.
• Log lines like error [SocialMediaService]: Error while sending saving updates: appear without any detail — the real cause is silently lost.
• Changes all six catch handlers to log ${e.message} in the message and pass e.stack as the trace argument.

Test plan

• Confirm next SocialMediaService exception in deploy logs includes the error message + stack