Session storage: sliding-idle expiry policy with configurable per-role limits

[thlpkee20-wq]

Description

All sessions currently share the same idle window. Add sliding-idle expiry with per-role limits (e.g. admins expire quicker than investors). Ensure the expiry recalculation is race-safe under concurrent requests.

Requirements and context

• Must be secure, tested, and documented
• Should be efficient and easy to review
• Relevant code: src/lib/sessionStore.ts, src/middleware/session.ts
• Recalculation uses atomic UPDATE

Suggested execution

• Fork the repo and create a branch
• git checkout -b feat/session-sliding-idle-per-role
• Implement changes
  • Add per-role idle config
  • Atomic touch UPDATE
  • Emit session.idle_extended counter
• Validate security and correctness assumptions

Test and commit

• Run tests
  • npm test
• Cover edge cases
  • Concurrent touches never extend past absolute cap
• Include test output and notes

Example commit message

feat: sliding-idle expiry per role

Guidelines

• Minimum 95 percent test coverage
• Clear documentation
• Timeframe: 96 hours