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/workflows/4-implementation/sprint-status/workflow.yaml

@@ -0,0 +1,25 @@
+# Sprint Status - Implementation Tracker
+name: sprint-status
+description: 'Summarize sprint status and surface risks. Use when the user says "check sprint status" or "show sprint status"'
+author: "BMad"
+
+# Critical variables from config
+config_source: "{project-root}/_bmad/bmm/config.yaml"
+user_name: "{config_source}:user_name"
+communication_language: "{config_source}:communication_language"
+document_output_language: "{config_source}:document_output_language"
+implementation_artifacts: "{config_source}:implementation_artifacts"
+
+# Workflow components
+installed_path: "{project-root}/_bmad/bmm/workflows/4-implementation/sprint-status"
+instructions: "{installed_path}/instructions.md"
+
+# Inputs
+sprint_status_file: "{implementation_artifacts}/sprint-status.yaml"
+
+# Smart input file references
+input_file_patterns:
+  sprint_status:
+    description: "Sprint status file generated by sprint-planning"
+    whole: "{implementation_artifacts}/sprint-status.yaml"
+    load_strategy: "FULL_LOAD"