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

.gitignore

@@ -0,0 +1,23 @@
+# Python
+__pycache__/
+*.py[cod]
+.venv/
+.mypy_cache/
+.pytest_cache/
+*.egg-info/
+
+# Rust / Trunk
+web/target/
+web/dist/
+web/.trunk/
+
+# Environment and local data
+.env
+*.log
+*.xdb
+
+# Editor
+.idea/
+.vscode/
+.DS_Store
+.playwright-mcp/