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

web/index.html

@@ -0,0 +1,23 @@
+<!doctype html>
+<html lang="en" data-bs-theme="dark">
+<head>
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <title>KCA — Key &amp; Certificate Authority</title>
+    <meta name="description" content="Web PKI management: keys, CSRs, certificates, CRLs and templates.">
+    <meta name="theme-color" content="#0a1720">
+    <meta name="color-scheme" content="dark">
+    <meta name="mobile-web-app-capable" content="yes">
+    <meta name="apple-mobile-web-app-title" content="KCA">
+    <link rel="manifest" href="/manifest.webmanifest">
+    <link rel="icon" type="image/svg+xml" href="/icons/icon.svg">
+    <link data-trunk rel="copy-file" href="pwa/manifest.webmanifest" data-target-path=".">
+    <link data-trunk rel="copy-file" href="pwa/sw.js" data-target-path=".">
+    <link data-trunk rel="copy-file" href="pwa/icons/icon.svg" data-target-path="icons">
+    <link data-trunk rel="rust" href="Cargo.toml">
+    <link data-trunk rel="css" href="vendor/bootstrap.min.css">
+    <link data-trunk rel="css" href="theme.css">
+    <link data-trunk rel="css" href="style.css">
+</head>
+<body></body>
+</html>