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>

src/skill_seekers/cli/parsers/workflows_parser.py

@@ -0,0 +1,85 @@
+"""Workflows subcommand parser."""
+
+from .base import SubcommandParser
+
+
+class WorkflowsParser(SubcommandParser):
+    """Parser for the workflows subcommand."""
+
+    @property
+    def name(self) -> str:
+        return "workflows"
+
+    @property
+    def help(self) -> str:
+        return "Manage enhancement workflow presets"
+
+    @property
+    def description(self) -> str:
+        return (
+            "List, inspect, copy, add, remove, and validate enhancement workflow "
+            "presets. Bundled presets ship with the package; user presets live in "
+            "~/.config/skill-seekers/workflows/."
+        )
+
+    def add_arguments(self, parser) -> None:
+        subparsers = parser.add_subparsers(dest="workflows_action", metavar="ACTION")
+
+        # list
+        subparsers.add_parser(
+            "list",
+            help="List all available workflows (bundled + user)",
+        )
+
+        # show
+        show_p = subparsers.add_parser(
+            "show",
+            help="Print YAML content of a workflow",
+        )
+        show_p.add_argument("workflow_name", help="Workflow name (e.g. security-focus)")
+
+        # copy
+        copy_p = subparsers.add_parser(
+            "copy",
+            help="Copy bundled workflow(s) to user dir for editing",
+        )
+        copy_p.add_argument(
+            "workflow_names",
+            nargs="+",
+            help="Bundled workflow name(s) to copy",
+        )
+
+        # add
+        add_p = subparsers.add_parser(
+            "add",
+            help="Install a custom YAML file into the user workflow directory",
+        )
+        add_p.add_argument(
+            "files",
+            nargs="+",
+            help="Path(s) to YAML workflow file(s) to install",
+        )
+        add_p.add_argument(
+            "--name",
+            help="Override the workflow filename (stem); only valid when adding a single file",
+        )
+
+        # remove
+        remove_p = subparsers.add_parser(
+            "remove",
+            help="Delete workflow(s) from the user directory (bundled workflows cannot be removed)",
+        )
+        remove_p.add_argument(
+            "workflow_names",
+            nargs="+",
+            help="User workflow name(s) to remove",
+        )
+
+        # validate
+        validate_p = subparsers.add_parser(
+            "validate",
+            help="Parse and validate a workflow by name or file path",
+        )
+        validate_p.add_argument(
+            "workflow_name", help="Workflow name or path to YAML file"
+        )