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-agent-builder/assets/save-memory.md

@@ -0,0 +1,29 @@
+---
+name: save-memory
+description: Explicitly save current session context to memory
+menu-code: SM
+---
+
+# Save Memory
+
+Immediately persist the current session context to memory.
+
+## Process
+
+1. **Read current index.md** — Load existing context
+
+2. **Update with current session:**
+   - What we're working on
+   - Current state/progress
+   - Any new preferences or patterns discovered
+   - Next steps to continue
+
+3. **Write updated index.md** — Replace content with condensed, current version
+
+4. **Checkpoint other files if needed:**
+   - `patterns.md` — Add new patterns discovered
+   - `chronology.md` — Add session summary if significant
+
+## Output
+
+Confirm save with brief summary: "Memory saved. {brief-summary-of-what-was-updated}"