fix: correction de toutes les erreurs CI — vet, lint, race detector et config

- clipboard_windows.go: remplacement unsafe.Pointer par unsafe.Add pour go vet 1.26
- clipboard_windows.go: correction errcheck (defer syscall) et ineffassign
- daemon_test.go: mockClipboard thread-safe avec sync.RWMutex (data race)
- daemon_test.go: correction errcheck sur go da.Run()
- server_test.go: vérification des erreurs json.Marshal
- config_test.go: vérification des erreurs MkdirAll/WriteFile
- peers.example.toml: mise à jour au format TOML actuel

peers.example.toml

@@ -1,10 +1,18 @@
 # clip-sync peers configuration
-# Copy this to peers.toml and edit your machines.
+# Copy this to ~/.config/clip-sync/peers.toml and edit your machines.
+#
+# Environment overrides:
+#   CLIP_SYNC_PORT=9137        override daemon.port
+#   CLIP_SYNC_POLL_MS=500      override daemon.poll_interval_ms
 
-listen = ":9137"
+[daemon]
+port = 9137
+poll_interval_ms = 500
 
-[peers]
-# name = "ip:port"
-# deepin    = "192.168.30.101:9137"
-# vivobook  = "192.168.20.161:9137"
-# openclaw1 = "192.168.30.27:9137"
+[[peers]]
+name = "bureau"
+addr = "192.168.1.10:9137"
+
+[[peers]]
+name = "portable"
+addr = "192.168.1.20:9137"