feat(ci): support explicit runtime secret mapping

Adds validated opt-in mapping from Gitea Actions secrets to QuickStack runtime environment variables.

.gitea/actions/quickstack-oci/deploy.test.mjs

@@ -6,6 +6,7 @@ import {
   deployExactImage,
   expandTokens,
   mergeEnvironment,
+  resolveSecretEnvironment,
   orderApplications,
   resolveDeploymentBranch,
   resolvePullRequestHeadBranch,
@@ -170,6 +171,24 @@ test("preserves response-only fields and existing environment secrets safely", (
   assert.equal(mergeEnvironment(app().envVars, { ENVIRONMENT: "new" }), "SECRET=preserved\nENVIRONMENT=new");
 });
 
+test("maps only explicitly declared Actions secrets into runtime environment", () => {
+  assert.deepEqual(
+    resolveSecretEnvironment(
+      { MINIO_ENDPOINT: "MINIO_ENDPOINT", MINIO_REGION: "MINIO_REGION" },
+      { MINIO_ENDPOINT: "https://minio.example.test", MINIO_REGION: "us-east-1" },
+    ),
+    { MINIO_ENDPOINT: "https://minio.example.test", MINIO_REGION: "us-east-1" },
+  );
+  assert.throws(
+    () => resolveSecretEnvironment({ MINIO_ENDPOINT: "MINIO_ENDPOINT" }, {}),
+    /Missing Actions secret MINIO_ENDPOINT/,
+  );
+  assert.throws(
+    () => resolveSecretEnvironment({ "INVALID-KEY": "MINIO_ENDPOINT" }, { MINIO_ENDPOINT: "value" }),
+    /Invalid secret environment key/,
+  );
+});
+
 test("postflight waits for the exact expected identity", async () => {
   let attempt = 0;
   const result = await verifyEndpoint(