Implement KCA: web reimplementation of XCA PKI workflows

- kaya backend with OIDC sessions, API tokens, Postgres/Tortoise models
- AES-256-GCM private key storage and full certificate/CSR/CRL domain logic
- Sycamore/WASM SPA for vaults, keys, requests, certificates, CRLs and templates
- imports/exports, XCA .xdb migration, Docker Compose stack and tests

.dockerignore

@@ -0,0 +1,10 @@
+.git
+server/.venv
+server/.mypy_cache
+server/tests
+web/target
+web/dist
+web/.trunk
+**/__pycache__
+*.pyc
+*.log