fix: abort installation on critical step failure

Previously all step errors were treated as warnings and installation
continued silently. Now critical steps (create dir, extract binary,
extract data/scripts, write config) will abort with an error message.
Non-critical steps (libusb, python venv, symlink, auto-start) still
warn and skip.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

edge-ai-platform/installer/app.go

@@ -200,20 +200,21 @@ func (inst *Installer) StartInstall(config InstallConfig) error {
 
 func (inst *Installer) runInstall(config InstallConfig) {
 	steps := []struct {
-		name    string
-		percent float64
-		fn      func(config InstallConfig) error
+		name     string
+		percent  float64
+		critical bool // if true, abort installation on failure
+		fn       func(config InstallConfig) error
 	}{
-		{"Creating installation directory", 5, inst.stepCreateDir},
-		{"Extracting server binary", 10, inst.stepExtractBinary},
-		{"Extracting models and firmware", 30, inst.stepExtractData},
-		{"Extracting scripts", 48, inst.stepExtractScripts},
-		{"Configuring system", 55, inst.stepConfigureSystem},
-		{"Setting up USB driver", 62, inst.stepSetupLibusb},
-		{"Setting up Python environment", 72, inst.stepSetupPython},
-		{"Writing configuration", 85, inst.stepWriteConfig},
-		{"Verifying installation", 90, inst.stepVerify},
-		{"Setting up auto-start launcher", 95, inst.stepAutoRestart},
+		{"Creating installation directory", 5, true, inst.stepCreateDir},
+		{"Extracting server binary", 10, true, inst.stepExtractBinary},
+		{"Extracting models and firmware", 30, true, inst.stepExtractData},
+		{"Extracting scripts", 48, true, inst.stepExtractScripts},
+		{"Configuring system", 55, false, inst.stepConfigureSystem},
+		{"Setting up USB driver", 62, false, inst.stepSetupLibusb},
+		{"Setting up Python environment", 72, false, inst.stepSetupPython},
+		{"Writing configuration", 85, true, inst.stepWriteConfig},
+		{"Verifying installation", 90, false, inst.stepVerify},
+		{"Setting up auto-start launcher", 95, false, inst.stepAutoRestart},
 	}
 
 	for _, step := range steps {
@@ -224,13 +225,21 @@ func (inst *Installer) runInstall(config InstallConfig) {
 		})
 
 		if err := step.fn(config); err != nil {
+			if step.critical {
+				inst.emitProgress(ProgressEvent{
+					Step:    step.name,
+					Message: fmt.Sprintf("Error: %s — %s", step.name, err),
+					Percent: step.percent,
+					IsError: true,
+				})
+				return // abort installation
+			}
 			inst.emitProgress(ProgressEvent{
 				Step:    step.name,
-				Message: fmt.Sprintf("Warning: %s — %s", step.name, err),
+				Message: fmt.Sprintf("Warning: %s — %s (skipped)", step.name, err),
 				Percent: step.percent,
 				IsError: true,
 			})
-			// Non-critical steps continue; critical ones are handled inside
 		}
 	}