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/bmb/bmad-workflow-builder/references/template-substitution-rules.md

@@ -0,0 +1,32 @@
+# Template Substitution Rules
+
+The SKILL-template provides a minimal skeleton: frontmatter, overview, and activation with config loading. Everything beyond that is crafted by the builder based on what was learned during discovery and requirements phases.
+
+## Frontmatter
+
+- `{module-code-or-empty}` → Module code prefix with hyphen (e.g., `bmb-`) or empty for standalone
+- `{skill-name}` → Skill functional name (kebab-case)
+- `{skill-description}` → Two parts: [5-8 word summary]. [trigger phrases]
+
+## Module Conditionals
+
+### For Module-Based Skills
+- `{if-module}` ... `{/if-module}` → Keep the content inside
+- `{if-standalone}` ... `{/if-standalone}` → Remove the entire block including markers
+- `{module-code}` → Module code without trailing hyphen (e.g., `bmb`)
+- `{module-setup-skill}` → Name of the module's setup skill (e.g., `bmad-builder-setup`)
+
+### For Standalone Skills
+- `{if-module}` ... `{/if-module}` → Remove the entire block including markers
+- `{if-standalone}` ... `{/if-standalone}` → Keep the content inside
+
+## Beyond the Template
+
+The builder determines the rest of the skill structure — body sections, phases, stages, scripts, external skills, headless mode, role guidance — based on the skill type classification and requirements gathered during the build process. The template intentionally does not prescribe these; the builder has the context to craft them.
+
+## Path References
+
+All generated skills use `./` prefix for skill-internal paths:
+- `./references/{reference}.md` — Reference documents loaded on demand
+- `./references/{stage}.md` — Stage prompts (complex workflows)
+- `./scripts/` — Python/shell scripts for deterministic operations