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

TODO.md

@@ -25,6 +25,21 @@ release" is exactly the contradiction
 
 # Completed Steps
 
+- 2026-09-22: Routed the last direct-to-stdout command output through
+  `internal/ui`
+  ([issue #149](https://git.eeqj.de/sneak/vaultik/issues/149)). The
+  `version`, `info`, `remote info`, `config`, and `database delete`
+  commands 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 go through its message
+  methods (styled, and `--quiet` silences them), while the data a command
+  exists to produce — the reports, the `snapshot list` table, `config get`
+  values, and the `--json` documents — is written plain. `--quiet`
+  silences the human reports and tables but never the `config get` value
+  or the `--json` documents, which a script depends on, and the
+  `database delete` confirmation prompt is always shown. The README
+  output-style section now states this rule.
+
 - 2026-09-22: Validated blob hashes, offsets and lengths read back from
   the destination before using them
   ([issue #155](https://git.eeqj.de/sneak/vaultik/issues/155)). A blob