fix: v0.4.2 — inspect_image used wrong DSM parameter contract

Live DSM API capture revealed the actual SYNO.Docker.Image/get
contract: a single JSON-encoded parameter named `identity` that
accepts both `name:tag` and `sha256:<hash>` forms. The 0.4.0 code
passed `name` + `tag` + `id` and was rejected by DSM with error 114.

Response shape also corrected — the endpoint returns flat top-level
fields (image, tag, id, digest, size, virtual_size, author,
docker_version, cmd, entrypoint, env, ports, volumes), NOT the
Docker-engine inspect shape with details.Config.* + RootFS.Layers
that the previous implementation assumed. Layer rendering removed;
digest / author / docker_version / volumes are now displayed.

Pre-resolution against list_images is no longer needed — the user
input goes straight into `identity` JSON-encoded.

Closes #4.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

CHANGELOG.md

@@ -2,6 +2,27 @@
 
 All notable changes to this project will be documented in this file.
 
+## [0.4.2] - 2026-05-18
+
+### Fixed
+
+- `inspect_image` (#4): the 0.4.0 implementation called
+  `SYNO.Docker.Image/get` with `name` + `tag` + `id` parameters, which
+  DSM rejected with error 114 ("invalid parameter"). Reverse-
+  engineering the live API capture revealed the correct contract:
+  one JSON-encoded parameter named `identity` that accepts either form:
+  - `name:tag` (e.g. `"gitea/gitea:1.26.1"`)
+  - `sha256:<hash>` (e.g. `"sha256:cd21e54e..."`)
+  The pre-resolution lookup against `list_images` is no longer needed —
+  the user input is JSON-encoded and passed straight through.
+- `inspect_image` response parsing: the endpoint does NOT return
+  `details.Config.*` / `RootFS.Layers` (the Docker-engine inspect shape
+  the previous code assumed). The actual top-level fields are `image`,
+  `tag`, `id`, `digest`, `size`, `virtual_size`, `author`,
+  `docker_version`, `cmd`, `entrypoint`, `env`, `ports`, `volumes`.
+  Layer rendering is removed (the endpoint does not surface layers);
+  digest, author, docker version, and volumes are now displayed.
+
 ## [0.4.1] - 2026-05-18
 
 ### Removed