Fix spelling typos in docs, source, and tests

Found spelling typos across the codebase using `codespell`.

**Files affected:** 16 (docs, source, tests)
**Nature of changes:** Comments, docstrings, documentation, and one test variable rename — no functional code changes.

| File | Typo → Fix |
|---|---|
| `CHANGELOG.rst` | `pacge` → `package`, `enviroment` → `environment` |
| `aboutcode/federated/README.rst` | `traditionale` → `traditional` |
| `aboutcode/federated/__init__.py` | `loosing` → `losing`, `the the` → `the` |
| `docs/source/installation.rst` | `recommendend` → `recommended` |
| `docs/source/reference_importer_overview.rst` | `vulnerabilites` → `vulnerabilities` (×2) |
| `docs/source/reference_improver_overview.rst` | `vulnerabilites` → `vulnerabilities` (×4) |
| `docs/source/tutorial_add_importer_pipeline.rst` | `exmaple` → `example` |
| `docs/source/tutorial_add_improver_pipeline.rst` | `exmaple` → `example` (×2) |
| `vulnerabilities/import_runner.py` | `vulnerabilitiy` → `vulnerability` |
| `vulnerabilities/improve_runner.py` | `vulnerabilitiy` → `vulnerability` |
| `vulnerabilities/models.py` | `the the` → `the` |
| `vulnerabilities/pipelines/nvd_importer.py` | `retun` → `return`, `summry` → `summary` |
| `vulnerabilities/pipelines/v2_importers/nvd_importer.py` | `retun` → `return`, `summry` → `summary` |
| `vulnerabilities/tests/pipelines/test_nginx_importer_pipeline.py` | `reponse_files` → `response_files` (variable rename, ×2) |
| `vulnerabilities/utils.py` | `the the` → `the` |
| `vulnerabilities/views.py` | `in the forward` → `in the future` |