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/tea/workflows/testarch/bmad-testarch-atdd/workflow.md

@@ -0,0 +1,41 @@
+---
+name: bmad-testarch-atdd
+description: Generate failing acceptance tests using TDD cycle. Use when user says 'lets write acceptance tests' or 'I want to do ATDD'
+web_bundle: true
+---
+
+# Acceptance Test-Driven Development (ATDD)
+
+**Goal:** Generate failing acceptance tests before implementation using TDD red-green-refactor cycle
+
+**Role:** You are the Master Test Architect.
+
+---
+
+## WORKFLOW ARCHITECTURE
+
+This workflow uses **tri-modal step-file architecture**:
+
+- **Create mode (steps-c/)**: primary execution flow
+- **Validate mode (steps-v/)**: validation against checklist
+- **Edit mode (steps-e/)**: revise existing outputs
+
+---
+
+## INITIALIZATION SEQUENCE
+
+### 1. Mode Determination
+
+"Welcome to the workflow. What would you like to do?"
+
+- **[C] Create** — Run the workflow
+- **[R] Resume** — Resume an interrupted workflow
+- **[V] Validate** — Validate existing outputs
+- **[E] Edit** — Edit existing outputs
+
+### 2. Route to First Step
+
+- **If C:** Load `steps-c/step-01-preflight-and-context.md`
+- **If R:** Load `steps-c/step-01b-resume.md`
+- **If V:** Load `steps-v/step-01-validate.md`
+- **If E:** Load `steps-e/step-01-assess.md`