fix: use context managers for all SQLite database connections

[satyakiabhijit]

🔗 Related Issue

• Open [Security/Reliability] Use context managers for all SQLite database connections #632

🎯 Rationale

Database connections were not using Python context managers, which can lead to connection leaks if exceptions occur before conn.close() is called. This refactoring ensures all connections are properly closed automatically.

📝 Summary of Changes

Refactored 24 SQLite database connections across 5 files to use Python context managers (with statement).

File	Connections Fixed
auth/auth_utils.py	7
core/utils.py	8
pages/Journaling.py	5
setup_database.py	3
migrate_db.py	1

🔧 Technical Details

Changed from manual conn.close() calls to using with sqlite3.connect() as conn: pattern. This follows Python best practices (PEP 343) and ensures connections are automatically closed even when exceptions occur.

✅ Testing

• All files pass Python syntax validation
• No functionality changes - pure refactoring

📋 Checklist

• Code follows project style guidelines
• Self-review completed
• No breaking changes

---