Initial scaffold: adapter framework + local folder reference adapter

Node/Express backend with a pluggable Adapter contract, a folder adapter
(safe non-destructive reject-to-trash, undo, keep/reject/skip), and a
vanilla JS swipe UI + generic settings form driven by each adapter's
configSchema.

.gitleaks.toml

@@ -0,0 +1,13 @@
+# Gitleaks config for SwipeAnything
+# useDefault is required so detection rules load.
+
+title = "SwipeAnything gitleaks"
+
+[extend]
+useDefault = true
+
+[allowlist]
+description = "Known false positives"
+paths = [
+  '''swipeanything\.config\.example\.json''',
+]