Initial import of fitme3070.pt platform

Plain-PHP fleet platform with id.andmore.pt SSO. Wires shared/platform-tools
as a submodule (platform_update, backups, git/migration tools) like the other
platforms.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

templates/error_500.php

@@ -0,0 +1,49 @@
+<?php
+// Generic 500 page for bootstrap failures (missing .env, unreachable DB, etc.).
+// Intentionally self-contained — runs before settings/cache/PDO are available,
+// so no env(), setting(), or DB calls here.
+//
+// The caller is responsible for sending http_response_code(500) before
+// `require`-ing this file.
+?>
+<!doctype html>
+<html lang="pt">
+<head>
+    <meta charset="utf-8">
+    <title>Erro</title>
+    <meta name="viewport" content="width=device-width,initial-scale=1">
+    <style>
+        body {
+            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
+            display: flex;
+            align-items: center;
+            justify-content: center;
+            min-height: 100vh;
+            margin: 0;
+            background: #161c18;
+            color: #cbbfb0;
+        }
+        .panel { text-align: center; max-width: 480px; padding: 2rem; }
+        .icon  { font-size: 2.5rem; margin-bottom: 1rem; opacity: .6; }
+        h2     { margin: 0 0 .75rem; }
+        p      { opacity: .7; margin: 0 0 1.5rem; }
+        button {
+            padding: .5rem 1.25rem;
+            border: 1px solid rgba(203, 191, 176, .3);
+            background: transparent;
+            color: #cbbfb0;
+            border-radius: 6px;
+            cursor: pointer;
+            font: inherit;
+        }
+    </style>
+</head>
+<body>
+    <div class="panel">
+        <div class="icon">⚠️</div>
+        <h2>Algo correu mal</h2>
+        <p>Estamos a resolver. Tente novamente em instantes.</p>
+        <button onclick="history.back()">← Voltar</button>
+    </div>
+</body>
+</html>