feat(sdk): AuthConfigs, JSON Schema, examples, and release checksum CI

Add craftlabs-auth-config.schema.json, Java AuthConfigs model with tests,
example configs aligned to BP-10, C/Java/auth-config documentation,
native header notes, RELEASING guide, and workflow to verify SDK
artifact checksums on release tags.

Made-with: Cursor

examples/config/school.selfhosted.json

@@ -0,0 +1,16 @@
+{
+  "schemaVersion": 1,
+  "provider": "selfhosted",
+  "scenario": "school",
+  "selfhosted": {
+    "baseUrl": "https://license.internal.example/api/v1",
+    "tenantKey": "district-west"
+  },
+  "features": {
+    "face": {},
+    "expression": {}
+  },
+  "school": {
+    "edgeDeviceId": "gate-02"
+  }
+}