Route direct-stdout command output through internal/ui (closes #149)

version, info, remote info, config, and database delete wrote plain text
straight to stdout, so they were unstyled and ignored --quiet. Output now
falls in two buckets, both governed by internal/ui.

Status lines and confirmations (config init, config set, database
delete) go through the ui message methods: styled, and --quiet silences
them. The data a command exists to produce is written plain, since a
marker would corrupt a table or a parsed document: the version, info, and
remote info reports, the snapshot list table, config get values, and the
--json documents. --quiet silences the human reports and tables but never
the config get value or the --json documents, which a script depends on.
The database delete confirmation prompt is always shown; it is an
interactive exchange the operator must see.

The pure-cli commands reach internal/ui through a small commandUI helper
that builds a ui.Writer on the command's stdout in quiet mode when
--quiet is set. NewForTesting now supplies a UI writer so the quiet gate
is never nil. The README output-style section states the resulting rule.

Model: opus-4-8

internal/cli/version_test.go

@@ -34,9 +34,9 @@ func runVersionCommand(t *testing.T) string {
 // the report is the version the binary was actually built with. The
 // test binary carries no -ldflags, so that is the "dev" default -- the
 // same string an untagged `make vaultik` build stamps a prefix of.
+//
+//nolint:paralleltest // executes a command that reads the global rootFlags
 func TestVersionCommandReportsBuildVersion(t *testing.T) {
-	t.Parallel()
-
 	out := runVersionCommand(t)
 
 	wantFirst := "vaultik " + globals.Version
@@ -55,9 +55,9 @@ func TestVersionCommandReportsBuildVersion(t *testing.T) {
 // being exactly "dev", so once untagged builds started carrying their
 // commit sha it would have gone silent and an unreleased binary would
 // have looked like a release.
+//
+//nolint:paralleltest // executes a command that reads the global rootFlags
 func TestVersionCommandFlagsDevelopmentBuild(t *testing.T) {
-	t.Parallel()
-
 	if !globals.IsDevVersion(globals.Version) {
 		t.Skipf("test binary was stamped with release version %q",
 			globals.Version)