Add header help icon and in-app docs search

- A ? icon in the top-right header deep-links to the doc most relevant to
  the current page (client-side path mapping, same pattern already used
  for top-nav active-link highlighting -- no server-side "current section"
  local exists to key off of instead). Falls back to the docs index.
- GET /docs/search does a plain line-substring search over the existing
  allowlisted doc set. No new dependency, stays usable with no internet
  access.

Bumps to v1.1.10.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KDEx8ghuZR61pqPXc6da9C

nodejs/package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "t42-sso-manager",
-  "version": "1.1.9",
+  "version": "1.1.10",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "t42-sso-manager",
-      "version": "1.1.9",
+      "version": "1.1.10",
       "license": "MIT",
       "dependencies": {
         "@fortawesome/fontawesome-free": "^7.3.0",