domain/record, runner: add DurationMS to RunRecord (T2.1, T2.2)

Add DurationMS int64 field to RunRecord and measure wall-clock
start→finish in RunJob; StartOnly jobs record 0.

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

src/domain/record.go

@@ -12,4 +12,5 @@ type RunRecord struct {
 	Detail     string `yaml:"detail"`
 	LogFile    string `yaml:"log_file,omitempty"`
 	Output     string `yaml:"output,omitempty"`
+	DurationMS int64  `yaml:"duration_ms,omitempty"`
 }

src/runner/runner.go

@@ -27,9 +27,12 @@ func RunJob(ctx context.Context, job *domain.Job, trigger string, logsDir string
 	var output string
 	var state string
 	var detail string
+	var durationMS int64
 	if job.StartOnly {
 		invocation := jobInvocation(context.Background(), *job)
 		state, detail, output = startJobOnly(invocation, *job, started)
+		// StartOnly jobs don't wait for process exit, so no meaningful duration.
+		durationMS = 0
 	} else {
 		var stdoutBuf strings.Builder
 		var stderrBuf strings.Builder
@@ -44,6 +47,7 @@ func RunJob(ctx context.Context, job *domain.Job, trigger string, logsDir string
 
 		err := command.Run()
 		duration := time.Since(started).Round(time.Millisecond)
+		durationMS = duration.Milliseconds()
 		output = formatOutput(stdoutBuf.String(), stderrBuf.String())
 		state, detail = runStateDetail(err, runCtx.Err(), duration)
 	}
@@ -64,6 +68,7 @@ func RunJob(ctx context.Context, job *domain.Job, trigger string, logsDir string
 		Detail:     detail,
 		LogFile:    logFile,
 		Output:     output,
+		DurationMS: durationMS,
 	}
 }