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/commands/bmad-bmm-create-prd.md

@@ -0,0 +1,6 @@
+---
+name: 'create-prd'
+description: 'Create a PRD from scratch. Use when the user says ""lets create a product requirements document"" or ""I want to create a new PRD""'
+---
+
+IT IS CRITICAL THAT YOU FOLLOW THIS COMMAND: LOAD the FULL @{project-root}/_bmad/bmm/workflows/2-plan-workflows/create-prd/workflow-create-prd.md, READ its entire contents and follow its directions exactly!