feat: Implement clipboard manager commands and history management

- Added command to clear clipboard history (`cmd_clear.go`).
- Implemented command to copy a history item back to the clipboard (`cmd_copy.go`).
- Created command to list clipboard history (`cmd_list.go`).
- Developed command to watch clipboard changes and store history (`cmd_watch.go`).
- Introduced configuration loading for logging and clipboard settings (`config.go`).
- Established main application logic with command registration and configuration handling (`main.go`).
- Implemented history management with loading, saving, and clearing functionality (`history.go`).
- Defined history item structure to store clipboard data (`history_item.go`).
- Added utility functions for hashing data and summarizing clipboard content (`hash.go`, `summary.go`).
- Updated dependencies in `go.sum`.

src/utils/hash.go

@@ -0,0 +1,11 @@
+package utils
+
+import (
+	"crypto/sha256"
+)
+
+// HashBytes returns a SHA256 hash of the given byte slice as a string.
+func HashBytes(data []byte) string {
+	h := sha256.Sum256(data)
+	return string(h[:])
+}

src/utils/summary.go

@@ -0,0 +1,20 @@
+package utils
+
+import (
+	"strconv"
+
+	"golang.design/x/clipboard"
+)
+
+func Summary(data []byte, format clipboard.Format) string {
+	if format == clipboard.FmtText {
+		if len(data) > 40 {
+			return string(data[:40]) + "..."
+		}
+		return string(data)
+	}
+	if format == clipboard.FmtImage {
+		return "[image] " + strconv.Itoa(len(data)) + " bytes"
+	}
+	return "[unknown format]"
+}