feat(resource): add virtual core resource types

Add 6 built-in virtual resource types (file, directory, commit, branch, tag,
tree) with equivalence metadata for content-hash and git-object identity
matching.

- YAML configs under examples/resource-types/
- Bootstrap registration with virtual types hidden from resource add scaffolding
- Equivalence criteria per spec (content_hash, merkle_hash, git SHA identity)
- Behave tests (83 scenarios), Robot tests, ASV benchmarks
- Documentation in docs/reference/resource_types_builtin.md

ISSUES CLOSED: #329

benchmarks/resource_type_virtual_core_bench.py

@@ -0,0 +1,81 @@
+"""ASV benchmarks for virtual core resource type YAML loading."""
+
+from __future__ import annotations
+
+from pathlib import Path
+from typing import Any
+
+import yaml
+
+from cleveragents.domain.models.core.resource_type import ResourceTypeSpec
+from cleveragents.resource.schema import ResourceTypeConfigSchema
+
+_EXAMPLES_DIR = Path(__file__).resolve().parent.parent / "examples" / "resource-types"
+
+_VIRTUAL_CORE_NAMES = ("file", "directory", "commit", "branch", "tag", "tree")
+_VIRTUAL_YAML_PATHS = {
+    name: _EXAMPLES_DIR / f"{name}.yaml" for name in _VIRTUAL_CORE_NAMES
+}
+
+
+class TimeVirtualCoreSchemaLoad:
+    """Benchmark virtual core resource type YAML schema loading."""
+
+    timeout = 60
+
+    def setup(self) -> None:
+        self.schema_cls = ResourceTypeConfigSchema
+        self.paths = dict(_VIRTUAL_YAML_PATHS)
+
+    def time_load_file_yaml(self) -> None:
+        self.schema_cls.from_yaml_file(self.paths["file"])
+
+    def time_load_directory_yaml(self) -> None:
+        self.schema_cls.from_yaml_file(self.paths["directory"])
+
+    def time_load_all_virtual_core(self) -> None:
+        for path in self.paths.values():
+            self.schema_cls.from_yaml_file(path)
+
+
+class TimeVirtualCoreDomainModelLoad:
+    """Benchmark virtual core resource type domain model creation."""
+
+    timeout = 60
+
+    def setup(self) -> None:
+        self.spec_cls = ResourceTypeSpec
+        self.configs: dict[str, dict[str, Any]] = {}
+        for name, path in _VIRTUAL_YAML_PATHS.items():
+            with open(path, encoding="utf-8") as f:
+                self.configs[name] = yaml.safe_load(f)
+
+    def time_file_from_config(self) -> None:
+        self.spec_cls.from_config(self.configs["file"])
+
+    def time_commit_from_config(self) -> None:
+        self.spec_cls.from_config(self.configs["commit"])
+
+    def time_all_virtual_core_from_config(self) -> None:
+        for config in self.configs.values():
+            self.spec_cls.from_config(config)
+
+
+class TimeVirtualCoreCliDict:
+    """Benchmark as_cli_dict rendering for virtual core types."""
+
+    timeout = 60
+
+    def setup(self) -> None:
+        self.specs: dict[str, ResourceTypeSpec] = {}
+        for name, path in _VIRTUAL_YAML_PATHS.items():
+            with open(path, encoding="utf-8") as f:
+                config: dict[str, Any] = yaml.safe_load(f)
+            self.specs[name] = ResourceTypeSpec.from_config(config)
+
+    def time_file_cli_dict(self) -> None:
+        self.specs["file"].as_cli_dict()
+
+    def time_all_virtual_core_cli_dict(self) -> None:
+        for spec in self.specs.values():
+            spec.as_cli_dict()