The README claims the query engine is available offline, but only the
merge half was: no subcommand produced the path / frontmatter /
last_modified / etag / size projection that GET /query returns.
`anwesen query` takes the same --vault and --query flags as merge and
writes that document to stdout, compact, one line. src/merge.rs becomes
src/oneshot.rs and holds both: one parse-and-load path, so the two
subcommands cannot drift in grammar or in how strictly they read a
vault. cli.rs shares one VaultQueryArgs between them for the same
reason. rfc3339_z moves from http.rs to query.rs, next to the projection
whose timestamp dialect it is.
Assumed a trailing newline on stdout is wanted here even though merge
writes none: the JSON body is one line for jq and shell pipelines, and
the newline terminates it rather than joining the document. Flag if
wrong.
The hurl harness now compares `anwesen query` against GET /query on the
fixture vault for four queries before running the suite, so a drift
between the two surfaces fails CI.
