Add task templates API and admin management

- Add TaskTemplate model with category and frequency support
- Add task template repository with CRUD and search operations
- Add task template service layer
- Add public API endpoints for templates (no auth required):
  - GET /api/tasks/templates/ - list all templates
  - GET /api/tasks/templates/grouped/ - templates grouped by category
  - GET /api/tasks/templates/search/?q= - search templates
  - GET /api/tasks/templates/by-category/:id/ - templates by category
  - GET /api/tasks/templates/:id/ - single template
- Add admin panel for task template management (CRUD)
- Add admin API endpoints for templates
- Add seed file with predefined task templates
- Add i18n translations for template errors

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

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

internal/handlers/task_template_handler.go

@@ -0,0 +1,106 @@
+package handlers
+
+import (
+	"net/http"
+	"strconv"
+
+	"github.com/gin-gonic/gin"
+
+	"github.com/treytartt/casera-api/internal/i18n"
+	"github.com/treytartt/casera-api/internal/services"
+)
+
+// TaskTemplateHandler handles task template endpoints
+type TaskTemplateHandler struct {
+	templateService *services.TaskTemplateService
+}
+
+// NewTaskTemplateHandler creates a new task template handler
+func NewTaskTemplateHandler(templateService *services.TaskTemplateService) *TaskTemplateHandler {
+	return &TaskTemplateHandler{
+		templateService: templateService,
+	}
+}
+
+// GetTemplates handles GET /api/tasks/templates/
+// Returns all active task templates as a flat list
+func (h *TaskTemplateHandler) GetTemplates(c *gin.Context) {
+	templates, err := h.templateService.GetAll()
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": i18n.LocalizedMessage(c, "error.failed_to_fetch_templates")})
+		return
+	}
+
+	c.JSON(http.StatusOK, templates)
+}
+
+// GetTemplatesGrouped handles GET /api/tasks/templates/grouped/
+// Returns all templates grouped by category
+func (h *TaskTemplateHandler) GetTemplatesGrouped(c *gin.Context) {
+	grouped, err := h.templateService.GetGrouped()
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": i18n.LocalizedMessage(c, "error.failed_to_fetch_templates")})
+		return
+	}
+
+	c.JSON(http.StatusOK, grouped)
+}
+
+// SearchTemplates handles GET /api/tasks/templates/search/
+// Searches templates by query string
+func (h *TaskTemplateHandler) SearchTemplates(c *gin.Context) {
+	query := c.Query("q")
+	if query == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "Query parameter 'q' is required"})
+		return
+	}
+
+	if len(query) < 2 {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "Query must be at least 2 characters"})
+		return
+	}
+
+	templates, err := h.templateService.Search(query)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": i18n.LocalizedMessage(c, "error.failed_to_search_templates")})
+		return
+	}
+
+	c.JSON(http.StatusOK, templates)
+}
+
+// GetTemplatesByCategory handles GET /api/tasks/templates/by-category/:category_id/
+// Returns templates for a specific category
+func (h *TaskTemplateHandler) GetTemplatesByCategory(c *gin.Context) {
+	categoryID, err := strconv.ParseUint(c.Param("category_id"), 10, 32)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid category ID"})
+		return
+	}
+
+	templates, err := h.templateService.GetByCategory(uint(categoryID))
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": i18n.LocalizedMessage(c, "error.failed_to_fetch_templates")})
+		return
+	}
+
+	c.JSON(http.StatusOK, templates)
+}
+
+// GetTemplate handles GET /api/tasks/templates/:id/
+// Returns a single template by ID
+func (h *TaskTemplateHandler) GetTemplate(c *gin.Context) {
+	id, err := strconv.ParseUint(c.Param("id"), 10, 32)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid template ID"})
+		return
+	}
+
+	template, err := h.templateService.GetByID(uint(id))
+	if err != nil {
+		c.JSON(http.StatusNotFound, gin.H{"error": i18n.LocalizedMessage(c, "error.template_not_found")})
+		return
+	}
+
+	c.JSON(http.StatusOK, template)
+}