feat: initial fluxer codebase import

fluxer_devops/cassandra/migrations/20251112134500_oidc_keys_refactor.cql

@@ -0,0 +1,14 @@
+CREATE TABLE IF NOT EXISTS fluxer.oidc_keys_by_kid (
+    kid text PRIMARY KEY,
+    alg text,
+    public_jwk text,
+    private_jwk text,
+    created_at timestamp
+);
+
+CREATE TABLE IF NOT EXISTS fluxer.oidc_key_status (
+    name text PRIMARY KEY,
+    active_kid text,
+    published_kids set<text>,
+    updated_at timestamp
+);