fix: resolve SSH key and errcheck linter issues

Deploy workflow fixes:
- Add tr -d '\r' to strip carriage returns from SSH key
- Set chmod 700 on .ssh directory for proper permissions
- Suppress ssh-keyscan stderr output

Handler code fixes:
- Check json.Encode() return values in errors.go (2 locations)
- Check json.Encode() return value in health.go
- Add log import to health.go
- Log encoding errors instead of silently ignoring

Resolves:
- "Load key: error in libcrypto" SSH deployment error
- 3 errcheck linter warnings

.github/workflows/deploy.yml

@@ -25,9 +25,10 @@ jobs:
 
           # Setup SSH
           mkdir -p ~/.ssh
-          echo "$SSH_PRIVATE_KEY" > ~/.ssh/deploy_key
+          chmod 700 ~/.ssh
+          echo "$SSH_PRIVATE_KEY" | tr -d '\r' > ~/.ssh/deploy_key
           chmod 600 ~/.ssh/deploy_key
-          ssh-keyscan -p $SSH_PORT -H $SSH_HOST >> ~/.ssh/known_hosts
+          ssh-keyscan -p $SSH_PORT -H $SSH_HOST >> ~/.ssh/known_hosts 2>/dev/null
 
           # Pull latest code and restart service
           echo "🔄 Pulling latest code and restarting service..."
@@ -70,7 +71,7 @@ jobs:
           echo "🔍 Verifying deployment..."
 
           # Setup SSH for verification
-          echo "$SSH_PRIVATE_KEY" > ~/.ssh/deploy_key
+          echo "$SSH_PRIVATE_KEY" | tr -d '\r' > ~/.ssh/deploy_key
           chmod 600 ~/.ssh/deploy_key
 
           # Test health endpoint