[CODE QUALITY] Extract magic numbers to centralized constants

[itigges22]

Description

Current State

Various timeout values, limits, and configuration numbers are hardcoded throughout the codebase. This makes it difficult to adjust settings and understand what values are used.

Examples found

// lib/permission-checker.ts:31
const CACHE_TTL = 5 * 60 * 1000; // 5 minutes

// lib/config.ts:35
windowMs: 15 * 60 * 1000, // 15 minutes

// lib/permission-toast.ts:10
const TOAST_COOLDOWN = 30000; // 30 seconds

// lib/supabase-server.ts:6
const FETCH_TIMEOUT = 30000; // 30 seconds

Desired Outcome

Create lib/constants.ts:

// Time constants (in milliseconds)
export const CACHE_TTL_MS = 5 * 60 * 1000; // 5 minutes
export const RATE_LIMIT_WINDOW_MS = 15 * 60 * 1000; // 15 minutes
export const TOAST_COOLDOWN_MS = 30 * 1000; // 30 seconds
export const FETCH_TIMEOUT_MS = 30 * 1000; // 30 seconds
export const AUTO_CLOCK_OUT_HOURS = 16;

// Limits
export const MAX_TIME_ENTRY_HOURS = 24;
export const MAX_WEEKLY_AVAILABILITY_HOURS = 168;
export const TIME_ENTRY_EDIT_WINDOW_DAYS = 14;

How to get started

1. Search for number literals: grep -rn "\d\+\s*\*\s*\d" lib/
2. Create lib/constants.ts with categorized exports
3. Replace hardcoded values with constants
4. Update imports in affected files

Acceptance Criteria

• lib/constants.ts exists with all timing and limit constants
• All files using magic numbers import from constants
• Constants are organized by category with comments