chore: Initialize Miyabi project with full planning

- Add .claude/ configuration (agents, commands, prompts, templates)
- Add comprehensive documentation:
  - WBS.md - Work Breakdown Structure
  - SPRINT_PLANNING.md - 4-sprint detailed plan
  - OPERATION_PLAN.md - Execution procedures
  - PRODUCT_SPEC.md - Product requirements
  - PREPARATION_OPS.md - Pre-sprint checklist
- Add PlantUML diagrams (wbs-diagram, gantt-chart)
- Configure Miyabi (.miyabi.yml)
- Set up Rust workspace structure

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

.env.example

@@ -0,0 +1,25 @@
+# GitHub Configuration
+# Get token at: https://github.com/settings/tokens
+# Required scopes: repo, workflow, admin:org (for Projects)
+GITHUB_TOKEN=ghp_your_github_token_here
+
+# Repository Information
+# Format: owner/repo (e.g., YourUsername/my-project)
+REPOSITORY=ShunsukeHayashi/miyabi-cli-standalone
+
+# Anthropic API Key (optional for local development)
+# Get key at: https://console.anthropic.com/
+# Required for running agents locally
+ANTHROPIC_API_KEY=sk-ant-your_anthropic_key_here
+
+# Device Identifier (for logging)
+DEVICE_IDENTIFIER=MyComputer
+
+# Agent Configuration
+LOG_DIRECTORY=.ai/logs
+REPORT_DIRECTORY=.ai/parallel-reports
+DEFAULT_CONCURRENCY=2
+
+# Development Options
+USE_TASK_TOOL=false
+USE_WORKTREE=false