feat: add ApplyPattern route for applying patterns with variables

## CHANGES
- Create `PatternApplyRequest` struct for request body parsing
- Implement `ApplyPattern` method for POST /patterns/:name/apply
- Register manual routes for pattern operations in `NewPatternsHandler`
- Refactor `Get` method to return raw pattern content
- Merge query parameters with request body variables in `ApplyPattern`
- Use `StorageHandler` for pattern-related storage operations

restapi/patterns.go

@@ -15,20 +15,70 @@ type PatternsHandler struct {
 
 // NewPatternsHandler creates a new PatternsHandler
 func NewPatternsHandler(r *gin.Engine, patterns *fsdb.PatternsEntity) (ret *PatternsHandler) {
-	ret = &PatternsHandler{
-		StorageHandler: NewStorageHandler(r, "patterns", patterns), patterns: patterns}
+	// Create a storage handler but don't register any routes yet
+	storageHandler := &StorageHandler[fsdb.Pattern]{storage: patterns}
+	ret = &PatternsHandler{StorageHandler: storageHandler, patterns: patterns}
 
-	// TODO: Add custom, replacement routes here
-	//r.GET("/patterns/:name", ret.Get)
+	// Register routes manually - use custom Get for patterns, others from StorageHandler
+	r.GET("/patterns/:name", ret.Get)                       // Custom method with variables support
+	r.GET("/patterns/names", ret.GetNames)                  // From StorageHandler
+	r.DELETE("/patterns/:name", ret.Delete)                 // From StorageHandler
+	r.GET("/patterns/exists/:name", ret.Exists)             // From StorageHandler
+	r.PUT("/patterns/rename/:oldName/:newName", ret.Rename) // From StorageHandler
+	r.POST("/patterns/:name", ret.Save)                     // From StorageHandler
+	// Add POST route for patterns with variables in request body
+	r.POST("/patterns/:name/apply", ret.ApplyPattern)
 	return
 }
 
-// Get handles the GET /patterns/:name route
+// Get handles the GET /patterns/:name route - returns raw pattern without variable processing
 func (h *PatternsHandler) Get(c *gin.Context) {
 	name := c.Param("name")
-	variables := make(map[string]string) // Assuming variables are passed somehow
-	input := ""                          // Assuming input is passed somehow
-	pattern, err := h.patterns.GetApplyVariables(name, variables, input)
+
+	// Get the raw pattern content without any variable processing
+	content, err := h.patterns.Load(name + "/" + h.patterns.SystemPatternFile)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, err.Error())
+		return
+	}
+
+	// Return raw pattern in the same format as the processed patterns
+	pattern := &fsdb.Pattern{
+		Name:        name,
+		Description: "",
+		Pattern:     string(content),
+	}
+	c.JSON(http.StatusOK, pattern)
+}
+
+// PatternApplyRequest represents the request body for applying a pattern
+type PatternApplyRequest struct {
+	Input     string            `json:"input"`
+	Variables map[string]string `json:"variables,omitempty"`
+}
+
+// ApplyPattern handles the POST /patterns/:name/apply route
+func (h *PatternsHandler) ApplyPattern(c *gin.Context) {
+	name := c.Param("name")
+
+	var request PatternApplyRequest
+	if err := c.ShouldBindJSON(&request); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	// Merge query parameters with request body variables (body takes precedence)
+	variables := make(map[string]string)
+	for key, values := range c.Request.URL.Query() {
+		if len(values) > 0 {
+			variables[key] = values[0]
+		}
+	}
+	for key, value := range request.Variables {
+		variables[key] = value
+	}
+
+	pattern, err := h.patterns.GetApplyVariables(name, variables, request.Input)
 	if err != nil {
 		c.JSON(http.StatusInternalServerError, err.Error())
 		return