feat(pyproject): release v1.7.0 — Python pyproject.toml version bump

Add internal/pyproject package with ReadVersion and WriteVersion for
pyproject.toml files. Reads [project].version (PEP 621) first, then
falls back to [tool.poetry].version. Section boundaries are detected
via TOML's rule that headers always start at the beginning of a line
(\n[ pattern), so inline arrays with [ characters don't interfere.

Config follows the established multi-value pattern:
- python.pyproject_toml: single path (opt-in, no default)
- python.pyproject_tomls: list for monorepos (overrides single)
- --pyproject flag overrides pyproject_toml and clears pyproject_tomls

100% per-package statement coverage maintained across all 14 packages;
FuzzReadVersion and FuzzWriteVersion added per fuzzing guidelines.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/content/usage.md

@@ -40,6 +40,7 @@ releaser --verbose --dry-run
 | `--tag-prefix <prefix>` | `""` | Prefix for version tags (e.g. `v` → `v1.2.3`) |
 | `--pom <path>` | `pom.xml` | Path to pom.xml relative to repo root |
 | `--gradle <path>` | — | Override `gradle.build_file` from config |
+| `--pyproject <path>` | — | Override `python.pyproject_toml` from config |
 | `--changelog-file <path>` | `CHANGELOG.md` | Path to changelog file |
 | `--release-env-file <path>` | `release.env` | Path for dotenv artifact; pass `""` to disable |
 | `--no-commit` | false | Update version files but stop before committing |