Release 2.1.0

ckq is now rogo (Latin "I ask"). Same engine, same index format, new
name everywhere: the package and binary, the on-disk names, the environment
variables, the URLs (bitboxx/rogo; the old ones redirect).

Distribution

• On crates.io as rogo (with the helper crate rogo-gpu):
  cargo install --locked rogo.
• A Homebrew tap over the release binaries: brew install bitboxx/tap/rogo.
• Every release archive carries signed build provenance;
  gh attestation verify <archive> --repo bitboxx/rogo checks it.

Renamed

• The package and binary ckq → rogo, the helper crate ckq-gpu → rogo-gpu.
• The index directory .ckq → .rogo, the ignore file .ckqignore →
  .rogoignore (flag --no-rogoignore), the cache ~/.cache/ckq →
  ~/.cache/rogo (models and daemon sockets, rogo-<alias>-…), the model
  check marker <file>.ckq-verified → <file>.rogo-verified.
• Every environment variable CKQ_* → ROGO_* (including the build-time
  ROGO_EMBED_GGUF, ROGO_EMBED_ALIAS).
• Release archives are rogo-<version>-<target>.

Migration

1. mv .ckq .rogo in every directory you indexed.
2. mv .ckqignore .rogoignore wherever you have one.
3. mv ~/.cache/ckq ~/.cache/rogo.
4. Rename any CKQ_* variable you set to ROGO_* (ROGO_IN_PROCESS,
   ROGO_DAEMON_IDLE_SECS, ROGO_DAEMON_TIMEOUT_SECS,
   ROGO_QUERY_DEVICE, ROGO_GGUF_FILE, ROGO_TIMING).

An index moved this way needs no rebuild: the index signature does not
contain the name, and nothing else in the store ever did.

Legacy handling

A command that finds no .rogo index but a .ckq/index.db fails with one
message naming the mv above; it never moves or writes anything itself.
Until .ckqignore is renamed, rogo keeps reading it — so results do not
change silently — and warns once on stderr; --index writes a default
.rogoignore only when neither file exists. A leftover .ckq directory is
skipped by the walker and left alone by --clean, exactly like a legacy
.ck. A model download that starts while ~/.cache/ckq/models still
exists says once which mv would have skipped it.