docs: improve skill documentation clarity

- Fix Provider Selection: default to Replicate when multiple keys available (matches code)
- Add Replicate column to Quality Presets table (normal→1K, 2k→2K)
- Add Replicate aspect ratio behavior (match_input_image when --ref without --ar)
- Remove stale Google Imagen reference from Aspect Ratios
- Add batch file format example with JSON schema to SKILL.md
- Note that batch paths resolve relative to batch file directory
- Move batch execution strategy in article-illustrator before numbered steps
- Fix translate image-language reminder to use standard markdown syntax
  with note to match article's own image syntax convention

skills/baoyu-article-illustrator/SKILL.md

@@ -118,6 +118,8 @@ Full template: [references/workflow.md](references/workflow.md#step-4-generate-o
 
 ⛔ **BLOCKING: Prompt files MUST be saved before ANY image generation.**
 
+**Execution strategy**: When multiple illustrations have saved prompt files and the task is now plain generation, prefer `baoyu-image-gen` batch mode (`build-batch.ts` → `--batchfile`) over spawning subagents. Use subagents only when each image still needs separate prompt iteration or creative exploration.
+
 1. For each illustration, create a prompt file per [references/prompt-construction.md](references/prompt-construction.md)
 2. Save to `prompts/NN-{type}-{slug}.md` with YAML frontmatter
 3. Prompts **MUST** use type-specific templates with structured sections (ZONES / LABELS / COLORS / STYLE / ASPECT)

skills/baoyu-article-illustrator/references/workflow.md

@@ -315,6 +315,10 @@ Prompt Files:
 
 **DO NOT** pass ad-hoc inline text to `--prompt` without first saving prompt files. The generation command should either use `--promptfiles prompts/NN-{type}-{slug}.md` or read the saved file content for `--prompt`.
 
+**Execution choice**:
+- If multiple illustrations already have saved prompt files and the task is now plain generation, prefer `baoyu-image-gen` batch mode (`build-batch.ts` -> `main.ts --batchfile`)
+- Use subagents only when each illustration still needs separate prompt rewriting, style exploration, or other per-image reasoning before generation
+
 **CRITICAL - References in Frontmatter**:
 - Only add `references` field if files ACTUALLY EXIST in `references/` directory
 - If style/palette was extracted verbally (no file), append info to prompt BODY instead