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>

_bmad/bmm/workflows/3-solutioning/create-architecture/architecture-decision-template.md

@@ -0,0 +1,12 @@
+---
+stepsCompleted: []
+inputDocuments: []
+workflowType: 'architecture'
+project_name: '{{project_name}}'
+user_name: '{{user_name}}'
+date: '{{date}}'
+---
+
+# Architecture Decision Document
+
+_This document builds collaboratively through step-by-step discovery. Sections are appended as we work through each architectural decision together._