feat: robust metric extraction with confidence score and proof snippets

- fixed Year-Prefix Bug in MetricParser
- added metric_confidence and metric_proof_text to database
- added Entity-Check and Annual-Priority to LLM prompt
- improved UI: added confidence traffic light and mouse-over proof tooltip
- restored missing API endpoints (create, bulk, wiki-override)

company-explorer/frontend/node_modules/postcss-import/lib/join-layer.js

@@ -0,0 +1,9 @@
+"use strict"
+
+module.exports = function (parentLayer, childLayer) {
+  if (!parentLayer.length && childLayer.length) return childLayer
+  if (parentLayer.length && !childLayer.length) return parentLayer
+  if (!parentLayer.length && !childLayer.length) return []
+
+  return parentLayer.concat(childLayer)
+}