Declare proprietary licensing and enforce permissive-only dependencies

Continuum is intended to be sold, so every dependency has to permit
distribution in closed-source commercial software. This crate carried
`license = "UNLICENSED"`, which is not valid SPDX and made `cargo deny`
fail outright; `LicenseRef-Proprietary` with `publish = false` is what
marks it first-party instead.

The note in deny.toml matters more than the allow list here: the ONNX
model weights this worker will load are licensed independently of the
`ort` crate, and `cargo deny` cannot see them at all. Ultralytics YOLO
and Obico's print-failure model are both AGPL-3.0 and cannot ship in a
commercial product - see continuum-common's docs/LICENSES.md, and pick a
permissive architecture before collecting training data rather than
retraining because of a licence.

Cargo.toml

@@ -3,7 +3,10 @@ name = "continuum-ai-worker"
 version = "0.1.0"
 edition = "2021"
 description = "Continuum AI worker - consumes camera frame batches from Redis Streams and runs print-failure detection"
-license = "UNLICENSED"
+# Proprietary: deliberately not an SPDX id, so cargo-deny treats it as
+# first-party. See docs/LICENSES.md in continuum-common.
+license = "LicenseRef-Proprietary"
+publish = false
 
 [[bin]]
 name = "continuum-ai-worker"