Fix achievement icons in launcher, allow opening OAuth URLs, live map docs

- Shared achievement icon catalogue; launcher resolves icon/background/border ids
- Tauri opener capability now allows http(s) URLs (fixes Discord sign-in)
- Rewrite live map docs, admin guide progression section

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DjMbLQujBHunCCu5GpsHaT

launcher/src-tauri/capabilities/default.json

@@ -15,6 +15,14 @@
     "core:window:allow-start-dragging",
     "core:window:allow-is-maximized",
     "dialog:allow-open",
-    "opener:allow-open-url"
+    {
+      "identifier": "opener:allow-open-url",
+      "allow": [
+        { "url": "https://*" },
+        { "url": "https://*/**" },
+        { "url": "http://*" },
+        { "url": "http://*/**" }
+      ]
+    }
   ]
 }