feat: initial commit — BMAD tooling, Claude memories, firmware scaffold

Adds the complete project foundation:
- BMAD BMM workflow tooling (_bmad/)
- Claude slash commands, skills, and project memories (.claude/)
- ESP32 firmware scaffold (PlatformIO + Waveshare e-ink driver)
- .gitignore excluding _bmad-output/ and .pio/ build artifacts

Planning artifacts (PRD, architecture, epics) are intentionally not
tracked — they live in _bmad-output/ per project convention.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.claude/skills/bmad-brainstorming/template.md

@@ -0,0 +1,15 @@
+---
+stepsCompleted: []
+inputDocuments: []
+session_topic: ''
+session_goals: ''
+selected_approach: ''
+techniques_used: []
+ideas_generated: []
+context_file: ''
+---
+
+# Brainstorming Session Results
+
+**Facilitator:** {{user_name}}
+**Date:** {{date}}