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/4-implementation/bmad-sprint-planning/checklist.md

@@ -0,0 +1,33 @@
+# Sprint Planning Validation Checklist
+
+## Core Validation
+
+### Complete Coverage Check
+
+- [ ] Every epic found in epic\*.md files appears in sprint-status.yaml
+- [ ] Every story found in epic\*.md files appears in sprint-status.yaml
+- [ ] Every epic has a corresponding retrospective entry
+- [ ] No items in sprint-status.yaml that don't exist in epic files
+
+### Parsing Verification
+
+Compare epic files against generated sprint-status.yaml:
+
+```
+Epic Files Contains:                Sprint Status Contains:
+✓ Epic 1                            ✓ epic-1: [status]
+  ✓ Story 1.1: User Auth              ✓ 1-1-user-auth: [status]
+  ✓ Story 1.2: Account Mgmt           ✓ 1-2-account-mgmt: [status]
+  ✓ Story 1.3: Plant Naming           ✓ 1-3-plant-naming: [status]
+                                      ✓ epic-1-retrospective: [status]
+✓ Epic 2                            ✓ epic-2: [status]
+  ✓ Story 2.1: Personality Model      ✓ 2-1-personality-model: [status]
+  ✓ Story 2.2: Chat Interface         ✓ 2-2-chat-interface: [status]
+                                      ✓ epic-2-retrospective: [status]
+```
+
+### Final Check
+
+- [ ] Total count of epics matches
+- [ ] Total count of stories matches
+- [ ] All items are in the expected order (epic, stories, retrospective)