M1: contracts and vectors (SPEC v0.1, schema 1)

contracts/openapi.yaml (OpenAPI 3.1, E-1..E-33, error shape and the
exhaustive error code enum, device bearer scheme), contracts/schema/
server-v1.sql (SPEC §14.1 verbatim), seven test-vector files per §14.5.5,
80 examples (every JSON body of §14.3.4, every error code, sync pull/push,
every FCM push type), and tools/contracts-check.py (stdlib-only reference
of §9.1, §9.3, §9.4 and §14.5.4 plus shape checks; the M1 gate).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

contracts/examples/E-5-apk-latest/response.json

@@ -0,0 +1,8 @@
+{
+  "version_code": 412,
+  "version_name": "2026.11.02-1a2b3c4",
+  "file_name": "kvitt-412.apk",
+  "size_bytes": 18234567,
+  "sha256": "9f2c4d1e8b7a6f5e4d3c2b1a0f9e8d7c6b5a4f3e2d1c0b9a8f7e6d5c4b3a2f1e",
+  "released_at": "2026-11-02T19:40:00.000Z"
+}