chore: Bump version to 2.8.0-dev

Start development cycle for v2.8.0.

Version updated in 5 locations:
- pyproject.toml
- src/skill_seekers/__init__.py
- src/skill_seekers/cli/__init__.py
- src/skill_seekers/mcp/__init__.py
- src/skill_seekers/mcp/tools/__init__.py

All version numbers synchronized to prevent Issue #248.

[Unreleased] section in CHANGELOG.md ready for v2.8.0 changes.

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 = "2.7.0"
+version = "2.8.0-dev"
 description = "Convert documentation websites, GitHub repositories, and PDFs into Claude AI skills"
 readme = "README.md"
 requires-python = ">=3.10"