Add Creative Writing expansion pack (#414)

* Add Creative Writing expansion pack
- 10 specialized writing agents for fiction and narrative design
- 8 complete workflows (novel, screenplay, short story, series)
- 27 quality checklists for genre and technical validation
- 22 writing tasks covering full creative process
- 8 professional templates for structured writing
- KDP publishing integration support

* Fix bmad-creative-writing expansion pack formatting and structure

- Convert all agents to standard BMAD markdown format with embedded YAML
- Add missing core dependencies (create-doc, advanced-elicitation, execute-checklist)
- Add bmad-kb.md customized for creative writing context
- Fix agent dependency references to only include existing files
- Standardize agent command syntax and activation instructions
- Clean up agent dependencies for beta-reader, dialog-specialist, editor, genre-specialist, narrative-designer, and world-builder

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Co-authored-by: Brian <bmadcode@gmail.com>

expansion-packs/bmad-creative-writing/tasks/generate-cover-prompts.md

@@ -0,0 +1,19 @@
+# ------------------------------------------------------------
+# tasks/generate-cover-prompts.md
+# ------------------------------------------------------------
+---
+task:
+  id: generate-cover-prompts
+  name: Generate Cover Prompts
+  description: Produce AI image generator prompts for front cover artwork plus typography guidance.
+  persona_default: cover-designer
+inputs:
+  - cover-brief.md
+steps:
+  - Extract mood, genre, imagery from brief.
+  - Draft 3‑5 alternative stable diffusion / DALL·E prompts (include style, lens, color keywords).
+  - Specify safe negative prompts.
+  - Provide font pairing suggestions (Google Fonts) matching genre.
+  - Output prompts and typography guidance to cover-prompts.md.
+output: cover-prompts.md
+...