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

internal/handlers/errors.go

@@ -79,7 +79,9 @@ func HandleError(w http.ResponseWriter, r *http.Request, err error) {
 			response.Message = appErr.Message
 		}
 
-		json.NewEncoder(w).Encode(response)
+		if err := json.NewEncoder(w).Encode(response); err != nil {
+			log.Printf("ERROR encoding JSON response: %v", err)
+		}
 		return
 	}
 
@@ -93,7 +95,9 @@ func HandleError(w http.ResponseWriter, r *http.Request, err error) {
 			message = "An error occurred. Please try again later."
 		}
 
-		w.Write([]byte("<div class='error'>" + message + "</div>"))
+		if _, err := w.Write([]byte("<div class='error'>" + message + "</div>")); err != nil {
+			log.Printf("ERROR writing HTMX error response: %v", err)
+		}
 		return
 	}
 

internal/handlers/health.go

@@ -2,6 +2,7 @@ package handlers
 
 import (
 	"encoding/json"
+	"log"
 	"net/http"
 	"time"
 )
@@ -35,5 +36,8 @@ func (h *HealthHandler) Check(w http.ResponseWriter, r *http.Request) {
 
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(http.StatusOK)
-	json.NewEncoder(w).Encode(response)
+	if err := json.NewEncoder(w).Encode(response); err != nil {
+		// Log error but don't change response status (already written)
+		log.Printf("ERROR encoding health check response: %v", err)
+	}
 }