feat: Add timezone configuration for Docker to ensure correct time handling in production and development environments

DOCKER_TIMEZONE_FIX.md

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+# Docker Timezone Configuration Fix
+
+## Problem
+Even after fixing the SQLite `datetime('now', 'localtime')` calls, notes posted at 10:00 still showed as 08:00 when running in Docker.
+
+## Root Cause
+**Docker containers run in UTC timezone by default!**
+
+When using `datetime('now', 'localtime')` in SQLite:
+- On local Windows machine: Uses Windows timezone (Europe/Warsaw) → ✅ Correct
+- In Docker container: Uses container timezone (UTC) → ❌ Wrong by 2 hours
+
+Example:
+```
+User posts at 10:00 Poland time (UTC+2)
+↓
+Docker container thinks local time is 08:00 UTC
+↓
+SQLite datetime('now', 'localtime') stores: 08:00
+↓
+Display shows: 08:00 (wrong!)
+```
+
+## Solution
+Set the Docker container timezone to Europe/Warsaw
+
+### 1. Updated Dockerfile (Production)
+
+```dockerfile
+# Use Node.js 22.11.0 as the base image
+FROM node:22.11.0
+
+# Set timezone to Europe/Warsaw (Polish timezone)
+ENV TZ=Europe/Warsaw
+RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
+
+# ... rest of Dockerfile
+```
+
+### 2. Updated Dockerfile.dev (Development)
+
+```dockerfile
+# Use Node.js 22.11.0 as the base image
+FROM node:22.11.0
+
+# Set timezone to Europe/Warsaw (Polish timezone)
+ENV TZ=Europe/Warsaw
+RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
+
+# ... rest of Dockerfile
+```
+
+### 3. Updated docker-compose.yml (Development)
+
+```yaml
+environment:
+  - NODE_ENV=development
+  - TZ=Europe/Warsaw
+```
+
+### 4. Updated docker-compose.prod.yml (Production)
+
+```yaml
+environment:
+  - NODE_ENV=production
+  - TZ=Europe/Warsaw
+  - NEXTAUTH_SECRET=...
+  - NEXTAUTH_URL=...
+```
+
+## How to Apply
+
+### Option 1: Rebuild Docker Images
+```bash
+# Stop containers
+docker-compose down
+
+# Rebuild images
+docker-compose build --no-cache
+
+# Start containers
+docker-compose up -d
+```
+
+### Option 2: For Production Deployment
+```bash
+# Pull latest code with fixes
+git pull
+
+# Rebuild production image
+docker-compose -f docker-compose.prod.yml build --no-cache
+
+# Restart
+docker-compose -f docker-compose.prod.yml up -d
+```
+
+## Verification
+
+After rebuilding and restarting, verify timezone inside container:
+
+```bash
+# Check timezone
+docker exec -it <container_name> date
+# Should show: Sat Oct  4 19:00:00 CEST 2025
+
+# Check Node.js sees correct timezone
+docker exec -it <container_name> node -e "console.log(new Date().toLocaleString('pl-PL', {timeZone: 'Europe/Warsaw'}))"
+# Should show current Polish time
+
+# Check SQLite sees correct timezone
+docker exec -it <container_name> node -e "const db = require('better-sqlite3')('./data/database.sqlite'); console.log(db.prepare(\"SELECT datetime('now', 'localtime')\").get());"
+# Should show current Polish time
+```
+
+## Why This Works
+
+1. **TZ Environment Variable**: Tells all processes (including Node.js and SQLite) what timezone to use
+2. **Symlink /etc/localtime**: Updates system timezone for the entire container
+3. **echo TZ > /etc/timezone**: Ensures the timezone persists
+
+Now when SQLite uses `datetime('now', 'localtime')`:
+- Container local time is 10:00 Poland time
+- SQLite stores: 10:00
+- Display shows: 10:00 ✅
+
+## Important Notes
+
+1. **Must rebuild images**: Just restarting containers is not enough - the timezone configuration is baked into the image
+2. **All existing data**: Old notes will still show incorrect times (they were stored in UTC)
+3. **New notes**: Will now display correctly
+4. **DST handling**: Europe/Warsaw automatically handles Daylight Saving Time transitions
+
+## Alternative Approach (Not Recommended)
+
+Instead of changing container timezone, you could:
+1. Store everything in UTC (like audit logs do with ISO format)
+2. Always convert on display
+
+But this requires more code changes and the current approach is simpler and more maintainable.
+
+## Files Modified
+
+1. `Dockerfile` - Added TZ configuration
+2. `Dockerfile.dev` - Added TZ configuration  
+3. `docker-compose.yml` - Added TZ environment variable
+4. `docker-compose.prod.yml` - Added TZ environment variable
+
+## Testing Checklist
+
+After deployment:
+- [ ] Container shows correct date/time with `docker exec <container> date`
+- [ ] Post a new note at known time (e.g., 10:30)
+- [ ] Verify note displays the same time (10:30)
+- [ ] Check both project notes and task notes
+- [ ] Verify audit logs still work correctly
+- [ ] Check task timestamps (date_started, date_completed)