Reorganize the repository for first public GitHub release. The project
becomes a fully self-contained, mass-market-friendly open-source build
of TigerScale.

Structure changes:
- firmware/TigerTag_Scale_V2/*.ino → src/main.cpp (PlatformIO-friendly)
- web/data/www/ → data/www/
- Stl Files/ → hardware/3d-models/ (lowercase, snake_case names)
- Hardware Links.txt → replaced by hardware/BOM.md (with vendor links)
- Removed Portuguese/Windows-specific docs (UPLOAD.md, WIRING.md, GITHUB_PUBLISH.md)

Firmware additions (Google Auth + token-based persistence):
- New endpoint POST /api/firebase/token accepts pre-obtained Firebase
  tokens (idToken, refreshToken, uid, email) from the OAuth bridge.
  Uses DynamicJsonDocument(4096) and proper chunked-body accumulation
  via request->_tempObject (Firebase ID tokens are ~1.5 KB → 2 chunks).
- isFirebaseConfigured() now accepts a refresh token alone (no password
  required) — enables Google Sign-In users to persist sessions.
- Boot sequence loads fbRefresh + fbUid from NVS and calls
  ensureFirebaseToken() (which handles both refresh-token and
  password-based auth paths).
- DELETE /api/firebase/auth wipes the new keys (fbRefresh, fbUid) too.

Tooling:
- platformio.ini and partitions.csv for PlatformIO support
- .gitattributes enforces LF line endings (no more CRLF noise)
- scripts/build_littlefs.sh and scripts/flash.sh (cross-platform helpers)
- .github/workflows/build.yml runs PlatformIO compile on every PR
- .github/ISSUE_TEMPLATE/, PULL_REQUEST_TEMPLATE.md

Documentation (English):
- README.md — hero section, badges, three install paths, architecture
- CHANGELOG.md — Keep-a-Changelog v2.0.0 release notes
- CONTRIBUTING.md, CODE_OF_CONDUCT.md (Contributor Covenant 2.1)
- docs/INSTALLATION.md — Web Installer / PlatformIO / Arduino IDE
- docs/HARDWARE.md — pinout, wiring tables, ASCII diagram, power budget
- docs/FIRMWARE.md — code architecture, REST API reference, NVS keys
- docs/FIREBASE_SETUP.md — TigerTag cloud explanation + self-hosted path
- docs/TROUBLESHOOTING.md — common issues across USB/Wi-Fi/Firebase/RFID
- hardware/BOM.md — vendor links with prices (~30 € total)
- hardware/3d-models/README.md — print settings, time/filament estimates

Web Installer (ESP Web Tools):
- web-installer/index.html — landing page + ESP Web Tools button
- web-installer/manifest.json — references the 5 binaries
- web-installer/firmware/ — bootloader.bin, partitions.bin, boot_app0.bin,
  firmware.bin, littlefs.bin (staged for GitHub Pages publication)

License: MIT.