feat: rewrite OCI publishing workflow to use Bazel-native rules

- Replace manual Docker builds with wasm_component_signed_oci_image
- Remove manual tool installations (wasm-tools, wkg, cosign)
- Use rules_wasm_component's native publishing capabilities
- Simplify component verification and signing workflow
- Follows documentation at rules-wasm-component.pulseengine.eu

Author: avrabe