chore: add BMAD agent workflows and configuration system

- Add comprehensive agent workflow definitions for 8 specialized roles (analyst, architect, developer, product manager, scrum master, technical writer, UX designer, QA engineer)
- Add 35+ workflow definitions covering analysis, planning, solutioning, and implementation phases
- Add BMAD configuration system with agent, task, tool, workflow, and file manifests
- Add BMM (Business Model Methodology) documentation including quick-start guides, architecture references, and workflow analysis
- Add test architecture knowledge base with 20+ testing patterns and best practices
- Add team configuration templates and party mode setup for collaborative development
- Establish foundation for enterprise agentic development framework with adaptive scaling capabilities

.bmad/docs/codex-instructions.md

@@ -0,0 +1,21 @@
+# BMAD Method - Codex Instructions
+
+## Activating Agents
+
+BMAD agents, tasks and workflows are installed as custom prompts in
+`$CODEX_HOME/prompts/bmad-*.md` files. If `CODEX_HOME` is not set, it
+defaults to `$HOME/.codex/`.
+
+### Examples
+
+```
+/bmad-bmm-agents-dev - Activate development agent
+/bmad-bmm-agents-architect - Activate architect agent
+/bmad-bmm-workflows-dev-story - Execute dev-story workflow
+```
+
+### Notes
+
+Prompts are autocompleted when you type /
+Agent remains active for the conversation
+Start a new conversation to switch agents