…nt framework

- Remove generic .bmad/bmm, .bmad/bmb, .bmad/core upstream scaffolding
- Add custom agent team: orchestrator, pm, architect, ux-designer, developer,
  tester, i18n-specialist, micropython-specialist, lvgl-mockui-specialist,
  hw-bootloader-specialist, security, scrum-master, doc-writer
- Add workflows: feature-development (9 stages incl. device validation),
  bug-fix, refactor, release
- Add adapters: copilot-instructions, cursor-rules, continue-dev
- Add team-config.md and BMAD.md with full project context
- Propagate nix-develop prefix to all make targets across all agent files
- Document correct manifest system (freeze tree, no per-file listing)
- Document i18n pipeline direction: specter_ui_en.json → sync-i18n →
  translation_keys.py (auto-generated); keys are UPPERCASE_UNDERSCORES
- Document boot chain: main.py shared, boot.py hardware-only, platform
  detection via sys.platform, /flash mount differences
- Add auto-generated files rule: path-independent .gitignore patterns
- Add device validation stage to feature-development workflow with
  test-first triage loop (fix test before blaming implementation)
- Update .gitignore: lang_*.bin, language_config.json, translation_keys.py
- Update CLAUDE.md with corrected pipeline and key locations