fix(footer): navigate to / instead of /home on Back to Home

Reported: clicking Back to Home in the sticky footer surfaced
Streamlit's "Page not found — Running the app's main page" message
in the user's build.

Root cause: ``url_path="home"`` on the home page's ``st.Page``
registration is treated as an alias for the default page in some
Streamlit minor versions, but the user's build doesn't honour the
alias for the page that ALSO has ``default=True``. The default page
is served at the root URL ``/``; ``/home`` is treated as a missing
page on that build.

Switch the footer anchor's href from ``"home"`` (which resolved to
``/home`` from any tool-page URL) to ``"./"`` (resolves to the
current document's directory, which on a single-segment URL is the
server root → default page → Home). Robust across Streamlit minor
versions regardless of how the url_path alias is interpreted.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/gui/components/_legacy.py

@@ -619,7 +619,15 @@ def render_sticky_footer() -> None:
       div.id = 'datatools-sticky-footer';
       var a = doc.createElement('a');
       a.className = 'datatools-sticky-footer-link';
-      a.href = 'home';
+      // Navigate to the app root (``/``) instead of ``/home``. The
+      // home page is registered with ``default=True``, which serves
+      // it at the root URL. ``/home`` is NOT a recognized URL on
+      // every Streamlit minor version even with ``url_path="home"``
+      // — some builds reserve the alias only for non-default pages.
+      // Using ``./`` is robust against both: it resolves to the
+      // current document's directory, which on a single-segment
+      // tool-page URL like ``/01_deduplicator`` is the server root.
+      a.href = './';
       a.target = '_self';
       a.textContent = label;
       div.appendChild(a);