chore(deps): clear every npm audit and pip-audit finding

Frontend:
    - react-router/-dom 7.18.1 -> 7.18.2. The RSC-mode CSRF advisory was carried
      as a documented exception in the audit gate because its only fix was the
      8.3.0 major; upstream backported it, so the exemption lapsed on its own --
      an entry only holds while fixAvailable.isSemVerMajor is true. The allowlist
      is now empty; the machinery stays for the next one.
    - dompurify 3.4.12 -> 3.4.13. Ships in the app, but the path is unreachable:
      no hooks registered, IN_PLACE never used.
    - js-yaml override ^4.3.0 -> ^5.2.3 (fix not backported below 5.x, so a
      major) and nanoid override ^3.3.18. Both dev-only, via eslint and postcss.
      eslintrc calls only load(), on the legacy .eslintrc.yml path this repo does
      not use; eslint, vite build and 2861 frontend tests pass on it.

    Backend:
    - cryptography >=48.0.1 -> >=50.0.0, aiohttp >=3.14.0 -> >=3.14.3, pyopenssl
      >=26.3.0 -> >=26.4.0. CI resolves from scratch and was already installing
      the fixed releases; the floors cover the case CI does not, an existing venv
      where >= is satisfied and `pip install -r` upgrades nothing. pyOpenSSL has
      to move with cryptography -- each release caps it to a narrow window, so a
      stale pyOpenSSL pins cryptography below its own fix line.

static/index.html

@@ -26,7 +26,7 @@
 
     <!-- Splash screens for iOS -->
     <link rel="apple-touch-startup-image" href="/img/android-chrome-512x512.png" />
-    <script type="module" crossorigin src="/assets/index-DPZgvI9N.js"></script>
+    <script type="module" crossorigin src="/assets/index-DjrhopFm.js"></script>
     <link rel="stylesheet" crossorigin href="/assets/index-C_6BSgrK.css">
   </head>
   <body>