refactor(msg): single space between keyword and message, improve config suggestions

Tightens keyword formatting (ok/FAIL/hint/etc.) from two spaces to one.
Makes config key suggestions more generous: normalises spaces to
underscores, matches against leaf segments, and uses substring matching.
Updates all golden files.

testdata/import-merge.ct

@@ -2,7 +2,7 @@
 $ pda set existing@mrg old-value
 $ fecho dumpfile {"key":"existing","value":"updated","encoding":"text"} {"key":"new","value":"hello","encoding":"text"}
 $ pda import mrg --file dumpfile
-  ok  restored 2 entries into @mrg
+  ok restored 2 entries into @mrg
 $ pda get existing@mrg
 updated
 $ pda get new@mrg