chore: Bump development version to 2.8.0-dev

After releasing v2.7.1 hotfix, development branch returns to 2.8.0-dev
for continued feature development.

Version Changes:
- pyproject.toml: 2.7.1 → 2.8.0-dev
- src/skill_seekers/__init__.py: 2.7.1 → 2.8.0-dev
- src/skill_seekers/cli/__init__.py: 2.7.1 → 2.8.0-dev
- src/skill_seekers/mcp/__init__.py: 2.7.1 → 2.8.0-dev
- src/skill_seekers/mcp/tools/__init__.py: 2.7.1 → 2.8.0-dev

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "skill-seekers"
-version = "2.7.1"
+version = "2.8.0-dev"
 description = "Convert documentation websites, GitHub repositories, and PDFs into Claude AI skills"
 readme = "README.md"
 requires-python = ">=3.10"