Stamp Docker image version from the host; flush profiles on error exit (closes #75)

script/docker and script/cibuild compute the version (via script/version),
commit and build date on the host and pass them as build args; the
Dockerfile no longer runs git, which always returned "unknown" because
the build context excludes .git. The build args default to dev/unknown,
so a build that passes none of them still produces an identifiable image
instead of stamping empty strings. A dirty tree is reflected through
script/version's -dirty suffix.

main now exits via os.Exit(run()), so its deferred CPU/heap profile
writers flush before the process ends, and Entry returns a status code
instead of calling os.Exit. Each command ran its operation in an fx
goroutine that called os.Exit(1) on failure, discarding those profiles
and the PID-lock release; they now route the error to the return path
through one RunOperation helper. errReported keeps Entry from printing an
already-reported failure twice.

model: claude-opus-4-8

internal/cli/entry.go

@@ -1,6 +1,7 @@
 package cli
 
 import (
+	"errors"
 	"io"
 	"os"
 	"strings"
@@ -19,7 +20,11 @@ const shortCommitLen = 12
 // flag is present in os.Args — see bannerSuppressedInArgs), executes the
 // root cobra command, and routes any returned error through the
 // ui.Writer so the user sees a properly formatted "🛑 ERROR:" line.
-func Entry() {
+//
+// It returns the process exit code (0 on success, 1 on error) rather
+// than calling os.Exit, so that main's deferred profile writers run
+// before the process ends. See run in cmd/vaultik/main.go.
+func Entry() int {
 	emitStartupBanner(os.Args[1:], os.Stdout)
 
 	rootCmd := NewRootCommand()
@@ -27,9 +32,19 @@ func Entry() {
 
 	err := rootCmd.Execute()
 	if err != nil {
-		ReportErrorf("%s", err.Error())
-		os.Exit(1)
+		// An operation that ran inside the fx app has already reported
+		// its own failure (and suppressed it under --json); errReported
+		// says so. Printing it again here would double the error line.
+		// Every other error — bad arguments, a config that would not
+		// load — reaches Entry unreported, so it is shown here.
+		if !errors.Is(err, errReported) {
+			ReportErrorf("%s", err.Error())
+		}
+
+		return 1
 	}
+
+	return 0
 }
 
 // emitStartupBanner writes the startup banner to w unless args (the