feat(index): add explainable auto-categorization in generate_index (#230)

* Add script to generate skills index from markdown files

This script generates an index of skills from markdown files in a specified directory, inferring categories and extracting metadata.

* chore: sync generated registry files [ci skip]

* Add unit tests for category inference functions

* chore: sync generated registry files [ci skip]

* Add Smart Auto-Categorization Guide

Added comprehensive guide for smart auto-categorization of skills, detailing the process, current status, category distribution, and usage instructions.

* chore: sync generated registry files [ci skip]

* chore: update star history chart

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: sck_0 <samujackson1337@gmail.com>

skill_categorization/tools/scripts/tests/test_generate_index_categorization.py

@@ -0,0 +1,59 @@
+#!/usr/bin/env python3
+
+import sys
+from pathlib import Path
+
+sys.path.append(str(Path(__file__).resolve().parents[1]))
+
+from generate_index import infer_category, normalize_category
+
+
+def assert_equal(actual, expected, label):
+    assert actual == expected, f"{label}: expected={expected!r} actual={actual!r}"
+
+
+def run_tests():
+    category = normalize_category("Cloud DevOps")
+    assert_equal(category, "cloud-devops", "normalize category")
+
+    skill_info = {
+        "id": "secure-api-gateway",
+        "category": "uncategorized",
+        "name": "secure-api-gateway",
+        "description": "Harden OAuth and JWT authentication flows for APIs.",
+    }
+    metadata = {"category": "security"}
+    category, confidence, reason = infer_category(skill_info, metadata, "")
+    assert_equal(category, "security", "frontmatter category")
+    assert_equal(confidence, 1.0, "frontmatter confidence")
+    assert reason.startswith("frontmatter:"), reason
+
+    skill_info = {
+        "id": "kubernetes-rollout-checker",
+        "category": "uncategorized",
+        "name": "kubernetes-rollout-checker",
+        "description": "Validate container rollouts and deployment health.",
+    }
+    metadata = {}
+    category, confidence, reason = infer_category(skill_info, metadata, "")
+    assert_equal(category, "cloud-devops", "keyword category")
+    assert confidence >= 0.5, confidence
+    assert reason.startswith("keyword-match:"), reason
+
+    skill_info = {
+        "id": "vendorx-hyperflux",
+        "category": "uncategorized",
+        "name": "vendorx-hyperflux",
+        "description": "Internal helper without known taxonomy keywords.",
+    }
+    metadata = {}
+    category, confidence, reason = infer_category(skill_info, metadata, "")
+    assert_equal(category, "hyperflux", "dynamic category")
+    assert confidence > 0.0, confidence
+    assert reason.startswith("derived-from-id-token:"), reason
+
+    print("ok")
+
+
+if __name__ == "__main__":
+    run_tests()