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/build-world.md

@@ -0,0 +1,17 @@
+# ------------------------------------------------------------
+# 2. Build World
+# ------------------------------------------------------------
+---
+task:
+  id: build-world
+  name: Build World
+  description: Create a concise world guide covering geography, cultures, magic/tech, and history.
+  persona_default: world-builder
+inputs:
+  - concept-brief.md
+steps:
+  - Summarize key themes from concept.
+  - Draft World Guide using world-guide-tmpl.
+  - Execute tasks#advanced-elicitation.
+output: world-guide.md
+...