feat: add category and effect as first-class fields in extension schema (#2899)

* feat: add category and effect as first-class fields in extension schema

Add `category` and `effect` as optional fields in the extension schema
(`extension.yml`) and community catalog (`catalog.community.json`).

Schema changes:
- Valid categories: docs, code, process, integration, visibility
- Valid effects: read-only, read-write
- Both fields are optional (backward-compatible with existing extensions)
- Validation raises ValidationError for invalid values when present

Propagation:
- Added `category` and `effect` to all 108 entries in catalog.community.json
  (populated from the existing docs/community/extensions.md table)
- Updated extension template with commented category/effect fields
- Updated add-community-extension skill with new JSON template fields
- Updated `specify extension info` CLI output to display category/effect
- Added properties to ExtensionManifest class

Tests:
- test_valid_category: all 5 category values pass
- test_valid_effect: both effect values pass
- test_invalid_category: invalid value raises ValidationError
- test_invalid_effect: invalid value raises ValidationError
- test_category_and_effect_optional: omitting fields still works

Closes #2874

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: make category free-form, keep effect validated

Category is a free-form string (only validated as non-empty when present),
while effect remains restricted to 'read-only' or 'read-write'.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: address PR review feedback

- Add type guard before 'in' check for effect to prevent TypeError on
  unhashable YAML values (list/dict)
- Comment out category/effect in template so authors must opt in
- Use VALID_EFFECTS constant in test instead of hard-coded values

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: update category docstring to reflect free-form semantics

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* docs: clarify canonical extension effect values

---------

Co-authored-by: Manfred Riem <mnriem@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

tests/test_extensions.py

@@ -24,6 +24,7 @@ from specify_cli.extensions import (
     CatalogEntry,
     CORE_COMMAND_NAMES,
     DEFAULT_HOOK_PRIORITY,
+    VALID_EFFECTS,
     ExtensionManifest,
     ExtensionRegistry,
     ExtensionManager,
@@ -300,6 +301,69 @@ class TestExtensionManifest:
         with pytest.raises(ValidationError, match="Invalid version"):
             ExtensionManifest(manifest_path)
 
+    def test_valid_category(self, temp_dir, valid_manifest_data):
+        """Test manifest with various category values (free-form string)."""
+        import yaml
+
+        for category in ("docs", "code", "process", "integration", "visibility", "custom-category"):
+            valid_manifest_data["extension"]["category"] = category
+            manifest_path = temp_dir / "extension.yml"
+            with open(manifest_path, 'w') as f:
+                yaml.dump(valid_manifest_data, f)
+            manifest = ExtensionManifest(manifest_path)
+            assert manifest.category == category
+
+    def test_valid_effect(self, temp_dir, valid_manifest_data):
+        """Test manifest with valid effect values."""
+        import yaml
+
+        for effect in sorted(VALID_EFFECTS):
+            valid_manifest_data["extension"]["effect"] = effect
+            manifest_path = temp_dir / "extension.yml"
+            with open(manifest_path, 'w') as f:
+                yaml.dump(valid_manifest_data, f)
+            manifest = ExtensionManifest(manifest_path)
+            assert manifest.effect == effect
+
+    def test_invalid_category(self, temp_dir, valid_manifest_data):
+        """Test manifest with empty category raises ValidationError."""
+        import yaml
+
+        valid_manifest_data["extension"]["category"] = ""
+        manifest_path = temp_dir / "extension.yml"
+        with open(manifest_path, 'w') as f:
+            yaml.dump(valid_manifest_data, f)
+
+        with pytest.raises(ValidationError, match="Invalid extension.category"):
+            ExtensionManifest(manifest_path)
+
+    def test_invalid_effect(self, temp_dir, valid_manifest_data):
+        """Test manifest with invalid effect raises ValidationError."""
+        import yaml
+
+        valid_manifest_data["extension"]["effect"] = "write-only"
+        manifest_path = temp_dir / "extension.yml"
+        with open(manifest_path, 'w') as f:
+            yaml.dump(valid_manifest_data, f)
+
+        with pytest.raises(ValidationError, match="Invalid extension.effect"):
+            ExtensionManifest(manifest_path)
+
+    def test_category_and_effect_optional(self, temp_dir, valid_manifest_data):
+        """Test that omitting category and effect still passes validation."""
+        import yaml
+
+        # Ensure no category/effect in data
+        valid_manifest_data["extension"].pop("category", None)
+        valid_manifest_data["extension"].pop("effect", None)
+        manifest_path = temp_dir / "extension.yml"
+        with open(manifest_path, 'w') as f:
+            yaml.dump(valid_manifest_data, f)
+
+        manifest = ExtensionManifest(manifest_path)
+        assert manifest.category is None
+        assert manifest.effect is None
+
     def test_invalid_command_name(self, temp_dir, valid_manifest_data):
         """Test manifest with command name that cannot be auto-corrected raises ValidationError."""
         import yaml