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/1-analysis/bmad-agent-tech-writer/write-document.md

@@ -0,0 +1,20 @@
+---
+name: write-document
+description: Author a document following documentation best practices
+menu-code: WD
+---
+
+# Write Document
+
+Engage in multi-turn conversation until you fully understand the ask. Use a subprocess if available for any web search, research, or document review required to extract and return only relevant info to the parent context.
+
+## Process
+
+1. **Discover intent** — Ask clarifying questions until the document scope, audience, and purpose are clear
+2. **Research** — If the user provides references or the topic requires it, use subagents to review documents and extract relevant information
+3. **Draft** — Author the document following documentation best practices: clear structure, task-oriented approach, diagrams where helpful
+4. **Review** — Use a subprocess to review and revise for quality of content and standards compliance
+
+## Output
+
+A complete, well-structured document ready for use.