feat: add bandwidth display to runner capabilities panel

- Add BandwidthInfo struct for bandwidth test results
- Display download speed and latency in runner edit page
- Show when the bandwidth test was last performed
- Add locale string for bandwidth label

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

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

modules/structs/actions_capabilities.go

@@ -3,6 +3,16 @@
 
 package structs
 
+import "time"
+
+// BandwidthInfo holds network bandwidth test results
+type BandwidthInfo struct {
+	DownloadMbps float64   `json:"download_mbps"`
+	UploadMbps   float64   `json:"upload_mbps,omitempty"`
+	Latency      float64   `json:"latency_ms,omitempty"`
+	TestedAt     time.Time `json:"tested_at"`
+}
+
 // DiskInfo holds disk space information for a runner
 type DiskInfo struct {
 	Total       uint64  `json:"total_bytes"`
@@ -23,6 +33,7 @@ type RunnerCapability struct {
 	Features         *CapabilityFeatures `json:"features,omitempty"`
 	Limitations      []string            `json:"limitations,omitempty"`
 	Disk             *DiskInfo           `json:"disk,omitempty"`
+	Bandwidth        *BandwidthInfo      `json:"bandwidth,omitempty"`
 }
 
 // CapabilityFeatures represents feature support flags