refactor: consume kin-infer, kin-vector, kin-search, kin-blobs from registry

Replace inline implementations with thin wrappers delegating to
extracted standalone crates. kin-model now re-exports Hash256 from
kin-blobs. All deps reference the kin registry — zero sibling paths.

Author: troyjr4103

crates/kin-db/Cargo.toml

@@ -12,19 +12,23 @@ doctest = false
 
 [features]
 default = ["vector", "embeddings"]
-vector = []
+vector = ["dep:kin-vector"]
 embeddings = [
     "dep:ndarray",
     "dep:safetensors",
     "dep:hf-hub",
     "dep:tokenizers",
+    "dep:kin-infer",
 ]
 archive = ["rkyv"]
 gcs = ["object_store/gcp", "tokio", "bytes"]
 sql = ["rusqlite"]
 
 [dependencies]
 kin-model = { version = "0.1.0", path = "../kin-model", registry = "kin" }
+kin-infer = { version = "0.1.1", registry = "kin", optional = true }
+kin-vector = { version = "0.1.0", registry = "kin", optional = true }
+kin-search = { version = "0.1.0", registry = "kin" }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 thiserror = "2"