fix(deps): pin ort to =2.0.0-rc.11 so cargo install doesn't break

Reported by @gianpaj after trying \`cargo install ck-search\` on 0.7.6:
36 errors cascading out of ck-embed::mixedbread, all of the form
"cannot convert ort::Error<SessionBuilder> to anyhow::Error".

Root cause: cargo install (without --locked) ignores Cargo.lock and
re-solves dependencies from scratch. Our \`ort = "2.0.0-rc.11"\` is a
caret range that lets cargo pick 2.0.0-rc.12. rc.12 made
SessionOptionsPointer wrap a NonNull<OrtSessionOptions> which is
!Sync, which propagates up: SessionBuilder is no longer Sync, so
ort::Error<SessionBuilder> is no longer Send+Sync, so it can't be
?-converted into anyhow::Error (which requires both).

Workaround for users: \`cargo install ck-search --locked\` honors the
published lockfile. But that's a footgun we shouldn't ship with.

Real fix: pin to \`=2.0.0-rc.11\` exact so any resolution path picks
the version we tested against. Follow-up: evaluate rc.12 upgrade
separately — likely needs ck-embed::mixedbread to map ort errors
manually via .map_err instead of relying on `From` blanket impl.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: runonthespot

Cargo.toml

@@ -72,7 +72,13 @@ base64 = "0.22"
 sha2 = "0.10"
 hf-hub = { version = "0.4.3", default-features = false, features = ["ureq"] }
 tokenizers = "0.20.1"
-ort = { version = "2.0.0-rc.11", default-features = false, features = ["download-binaries", "tls-native", "ndarray", "std"] }
+# Pinned exactly to rc.11. ort 2.0.0-rc.12 made SessionOptionsPointer
+# !Sync, which removes Send+Sync from ort::Error<SessionBuilder> and
+# breaks `?`-conversion into anyhow::Error throughout ck-embed::mixedbread.
+# Without the `=` pin, a fresh `cargo install ck-search` (no --locked)
+# upgrades to rc.12 and 36 errors cascade. See:
+# https://github.com/BeaconBay/ck/pull/<TODO> for follow-up to evaluate rc.12.
+ort = { version = "=2.0.0-rc.11", default-features = false, features = ["download-binaries", "tls-native", "ndarray", "std"] }
 once_cell = "1.19"
 ndarray = { version = "0.17", default-features = false, features = ["std"] }
 num_cpus = "1.16"