docs(baoyu-cover-image): redirect codex-imagegen invocation through baoyu-image-gen --provider codex-cli

Replace the long inline `scripts/codex-imagegen.sh` invocation block in
SKILL.md with a pointer to references/codex-imagegen.md. The reference
documents the preferred `baoyu-image-gen --provider codex-cli` path and
keeps the direct-wrapper fallback for runtimes without baoyu-image-gen.

skills/baoyu-cover-image/SKILL.md

@@ -1,7 +1,7 @@
 ---
 name: baoyu-cover-image
 description: Generates article cover images with 5 dimensions (type, palette, rendering, text, mood) combining 11 color palettes and 7 rendering styles. Supports cinematic (2.35:1), widescreen (16:9), and square (1:1) aspects. Use when user asks to "generate cover image", "create article cover", or "make cover".
-version: 1.117.4
+version: 1.117.5
 metadata:
   openclaw:
     homepage: https://github.com/JimLiu/baoyu-skills#baoyu-cover-image
@@ -29,19 +29,7 @@ When this skill needs to render an image, resolve the backend in this order:
 2. **Saved preference** — if `EXTEND.md` sets `preferred_image_backend` to a backend available right now, use it.
 3. **Auto-select** (when the preference is `auto`, unset, or the pinned backend isn't available):
    - **Codex (`imagegen`)** — first, inspect your available-skills / tool inventory. If a skill named `imagegen` is listed, you are running inside Codex and MUST use it: invoke via the `Skill` tool with `skill: "imagegen"`, passing the saved prompt file's content (plus output path and aspect ratio per Codex `imagegen`'s own args). Codex `imagegen` is the official raster backend in that runtime and outranks any non-native skill (e.g., `baoyu-image-gen`) unless the user has explicitly pinned a different `preferred_image_backend`.
-   - **Codex via `codex exec` (`codex-imagegen`)** — if the current runtime does NOT expose a native `imagegen` skill but the `codex` CLI is on `PATH` and `codex login` is active (e.g., Claude Code with Codex CLI installed), invoke the `codex-imagegen` wrapper. **Path resolution**: `scripts/codex-imagegen.sh` lives at the plugin/repo root, NOT relative to your shell cwd. From this `SKILL.md`'s base directory, the wrapper is at `../../scripts/codex-imagegen.sh` — resolve to an absolute path before invoking. Command shape:
-     ```bash
-     <ABSOLUTE_PLUGIN_ROOT>/scripts/codex-imagegen.sh \
-       --image <absolute_output_path> \
-       --prompt-file <absolute_path_to_prompts/NN-cover-[slug].md> \
-       --aspect <ratio> \
-       [--ref <absolute_file>]... \
-       [--timeout <ms>] \
-       [--cache-dir ~/.cache/baoyu-codex-imagegen] \
-       [--log-file <absolute_jsonl_log_path>]
-     ```
-     `--timeout` defaults to 300000 (5 min) per codex exec attempt; raise it (e.g. `--timeout 600000` for 10 min) on slow networks or large prompts.
-     All input paths to the wrapper are auto-resolved against the wrapper's `process.cwd()` if you pass relative ones, but agents should pass absolute paths to be robust against cwd drift. Parse the single-line JSON on stdout. On `{"status":"ok",...}` proceed to Step 5. On `{"status":"error","error_kind":...}` report the `error_kind` to the user and (if retryable) ask whether to retry or fall back to another backend. The wrapper uses the user's Codex subscription — no `OPENAI_API_KEY` needed.
+   - **Codex via `codex exec` (`codex-imagegen`)** — if the current runtime exposes no native `imagegen` skill but the `codex` CLI is on `PATH` with an active `codex login`, route through `baoyu-image-gen --provider codex-cli` (preferred), or — if baoyu-image-gen is unavailable — invoke the bundled wrapper directly. Details, parameters, and the runtime-discovery procedure live in [references/codex-imagegen.md](references/codex-imagegen.md) — load that file only when this branch is selected.
    - **Other runtime-native tools** — if the runtime exposes a different native image tool (e.g., Hermes `image_generate`), use it the same way.
    - Otherwise, if exactly one non-native backend is installed (e.g., `baoyu-image-gen`), use it.
    - Otherwise (multiple non-native backends with no runtime-native tool), ask the user once — batch with any other initial questions.
@@ -228,7 +216,7 @@ Save to `prompts/cover.md`. Template: [references/workflow/prompt-template.md](r
    - `direct` usage → pass via `--ref` (use ref-capable backend)
    - `style`/`palette` → extract traits, append to prompt
 5. **Generate**: Call the chosen backend with the prompt file, output path, aspect ratio.
-   - **`codex-imagegen`**: invoke `<ABSOLUTE_PLUGIN_ROOT>/scripts/codex-imagegen.sh` (NOT a cwd-relative `./scripts/...` — resolve the absolute path from this skill's base directory: `../../scripts/codex-imagegen.sh`) with `--image <ABSOLUTE_output>` `--prompt-file <ABSOLUTE_prompts/01-cover-[slug].md>` `--aspect <ratio>` (add `--ref <ABSOLUTE_file>` per reference, `--cache-dir ~/.cache/baoyu-codex-imagegen` to enable the idempotency cache, `--timeout <ms>` to override the default 300000 / 5-min per-attempt limit on slow networks). All input paths to the wrapper are auto-resolved against its `process.cwd()` if relative, but passing absolutes is more robust. Read the stdout JSON; act on `status` and `error_kind`.
+   - **`codex-imagegen`**: see [references/codex-imagegen.md](references/codex-imagegen.md) for the invocation contract (preferred `baoyu-image-gen --provider codex-cli` path, runtime wrapper discovery, parameter notes, stdout schema, batch semantics).
    - **Codex `imagegen` (native)** or other runtime-native tools / `baoyu-image-gen` skill: per the rule in `## Image Generation Tools` above.
 6. On failure: auto-retry once