fix(verification): global backend/frontend fixes and protocol compliance`

[CFBruna]

What's New

• Backend:
  • Resolved ninja.errors.ConfigError in tests by implementing NINJA_SKIP_REGISTRY.
  • Fixed mypy strict mode errors (including NotRegistered usage).
  • Resolved bare except clauses and attribute references in store app.
  • Applied ruff formatting and lint fixes across the entire backend.
• Frontend:
  • Resolved eslint version conflict by downgrading to v9.
  • Fixed linting errors: strict typing (any), hooks dependencies, and unused code.
  • Fixed build errors: added missing Switch component and warning Badge variant.
• Documentation:
  • Updated task.md and walkthrough.md with verification protocol results.

Why

To ensure the project meets the "Verification Protocol" standards (Phase 16), achieving a clean state for both Backend (mypy, ruff, pytest) and Frontend (lint, build). This stability is required before proceeding to further feature development or deployment.

Testing

• Unit tests added/updated (pytest) -> Passed (279 tests)
• Manual test: Run npm run build (Frontend) -> Passed
• Manual test: Run uv run mypy . (Backend) -> Passed

Checklist

• Code follows Service Layer architecture
• No logic in Views/Admin
• MyPy strict compliance (for new files)
• Ruff linting passed