feat: enhancement workflow preset system with multi-target CLI

- Add YAML-based enhancement workflow presets shipped inside the package
  (default, minimal, security-focus, architecture-comprehensive, api-documentation)
- Add `skill-seekers workflows` subcommand: list, show, copy, add, remove, validate
- copy/add/remove all accept multiple names/files in one invocation with partial-failure behaviour
- `add --name` override restricted to single-file operations
- Add 5 MCP tools: list_workflows, get_workflow, create_workflow, update_workflow, delete_workflow
- Fix: create command _add_common_args() now correctly forwards each --enhance-workflow
  as a separate flag instead of passing the whole list as a single argument
- Update README: reposition as "data layer for AI systems" with AI Skills front and centre
- Update CHANGELOG, QUICK_REFERENCE, CLAUDE.md with workflow preset details
- 1,880+ tests passing

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

pyproject.toml

@@ -203,6 +203,7 @@ skill-seekers-stream = "skill_seekers.cli.streaming_ingest:main"
 skill-seekers-update = "skill_seekers.cli.incremental_updater:main"
 skill-seekers-multilang = "skill_seekers.cli.multilang_support:main"
 skill-seekers-quality = "skill_seekers.cli.quality_metrics:main"
+skill-seekers-workflows = "skill_seekers.cli.workflows_command:main"
 
 [tool.setuptools]
 package-dir = {"" = "src"}
@@ -213,7 +214,7 @@ include = ["skill_seekers*"]
 namespaces = false
 
 [tool.setuptools.package-data]
-skill_seekers = ["py.typed"]
+skill_seekers = ["py.typed", "workflows/*.yaml"]
 
 [tool.pytest.ini_options]
 testpaths = ["tests"]