`"now()"` stored as literal string instead of SQL timestamp

[Vachhani-Tapan]

🐛 Bug Description

update_last_active() and upsert_staged_file() use "now()" as a plain string value in the update dict. The Supabase Python client serializes this to JSON, so PostgreSQL receives the literal string "now()" instead of executing the SQL now() function.

🔁 Steps to Reproduce

1. Call update_last_active() for any user.
2. Query the last_active field in the database.
3. Observe the field contains the string "now()" instead of a real timestamp.

✅ Expected Behavior

The last_active and updated_at fields should contain a proper UTC timestamp representing the current time.

❌ Actual Behavior

All timestamps are set to the literal string "now()", corrupting user activity tracking. Features like "last active X ago" display incorrect values, and admin dormant-user detection based on last_active will not work.

🌍 Environment

Field	Value
OS	Any
VS Code version	Any
GitPhone extension version	Any
Python version	Any

📋 Additional Context

Files: backend/supabase_service.py:54, backend/supabase_service.py:92
Fix: Use a raw SQL expression (supabase.rpc()) or the Supabase schema function to properly emit SQL now().

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[Vachhani-Tapan]

/claim Assign me under ECSoC'26

[ankittroy-21]

@Vachhani-Tapan Assigned to you