chore: upgrade jQuery and introduce Migrate for safe modernization

Upgrade jQuery from 1.7.1 to 1.9.1 and jQuery UI from 1.8.18 to 1.9.1 to
bridge toward a modern codebase. While 1.9.1 is still outdated by today's
standards, it introduces critical deprecation warnings and improves
compatibility with newer APIs, serving as a necessary intermediate step
before a full jump to jQuery 3.x.

Importantly, this commit adds jQuery Migrate 1.2.1 from the official CDN
to detect and log deprecated usage patterns that would otherwise break
silently during future upgrades. Migrate will surface issues like:
- Calls to deprecated methods (.live(), .bind() in certain contexts)

These warnings are essential for identifying technical debt in our
existing JavaScript (e.g., in application.js)
and planning safe refactors.

This is Step 1 of a phased migration strategy:
1. Upgrade to jQuery 1.9.1 + Migrate → current commit
2. Audit console warnings and modernize code
3. Upgrade to jQuery 3.7.1 with jquery-migrate-3.4.1
4. Remove Migrate once all deprecations are resolved

The use of CDN-hosted assets simplifies version management and ensures
we’re not bundling outdated copies.

Note: Source map 404s may appear (jquery.min.map) — these are harmless
and expected for older jQuery versions. We will address them in a later
upgrade when moving to modern, actively supported releases.

Author: RafaelJohn9

layouts/partials/footer.html

@@ -11,8 +11,9 @@
   <img src="{{ relURL "images/icons/chevron-up@2x.png" }}" width="20" height="20" alt="scroll-to-top"/>
 </a>
 
-<script src="{{ relURL "js/jquery-1.7.1.min.js" }}"></script>
-<script src="{{ relURL "js/jquery-ui-1.8.18.custom.min.js" }}"></script>
+<script src="https://code.jquery.com/jquery-1.9.1.min.js"></script>
+<script src="https://code.jquery.com/ui/1.9.1/jquery-ui.min.js"></script>
+<script src="https://code.jquery.com/jquery-migrate-1.2.1.js"></script>
 <script src="{{ relURL "js/jquery.defaultvalue.js" }}"></script>
 <script src="{{ relURL "js/session.min.js" }}"></script>
 {{ $js := resources.Get "js/application.js" | resources.ExecuteAsTemplate "js/application.js" . | resources.Minify | fingerprint }}