Add generate-share-package endpoint for residence sharing

- Add POST /api/residences/:id/generate-share-package/ endpoint
- Add SharePackageResponse DTO with share code and metadata
- Add GenerateSharePackage service method to create one-time share codes
- Update JoinWithCode to deactivate share code after successful use

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

internal/handlers/residence_handler.go

@@ -207,6 +207,37 @@ func (h *ResidenceHandler) GenerateShareCode(c *gin.Context) {
 	c.JSON(http.StatusOK, response)
 }
 
+// GenerateSharePackage handles POST /api/residences/:id/generate-share-package/
+// Returns a share code with metadata for creating a .casera package file
+func (h *ResidenceHandler) GenerateSharePackage(c *gin.Context) {
+	user := c.MustGet(middleware.AuthUserKey).(*models.User)
+
+	residenceID, err := strconv.ParseUint(c.Param("id"), 10, 32)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": i18n.LocalizedMessage(c, "error.invalid_residence_id")})
+		return
+	}
+
+	var req requests.GenerateShareCodeRequest
+	// Request body is optional (for expires_in_hours)
+	c.ShouldBindJSON(&req)
+
+	response, err := h.residenceService.GenerateSharePackage(uint(residenceID), user.ID, req.ExpiresInHours)
+	if err != nil {
+		switch {
+		case errors.Is(err, services.ErrResidenceNotFound):
+			c.JSON(http.StatusNotFound, gin.H{"error": i18n.LocalizedMessage(c, "error.residence_not_found")})
+		case errors.Is(err, services.ErrNotResidenceOwner):
+			c.JSON(http.StatusForbidden, gin.H{"error": i18n.LocalizedMessage(c, "error.not_residence_owner")})
+		default:
+			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		}
+		return
+	}
+
+	c.JSON(http.StatusOK, response)
+}
+
 // JoinWithCode handles POST /api/residences/join-with-code/
 func (h *ResidenceHandler) JoinWithCode(c *gin.Context) {
 	user := c.MustGet(middleware.AuthUserKey).(*models.User)