settings: drop the broker-list line from the import lede

Removed "Trading 212 is recognised natively and other formats (IBKR,
Fidelity, Schwab…) are auto-detected" from the import section's
lede paragraph — internal/marketing noise that doesn't help the user
once they're already on the import screen with a file picker in
front of them. Kept the surrounding sentence ("Drop a portfolio CSV
from any broker. We'll parse it…") and the T212 export-path hint
since the latter is concrete instructional content for T212 users.

app/templates/settings.html

@@ -98,10 +98,8 @@
     <details class="settings-section" id="import" open>
       <summary class="settings-section__head">Import portfolio (CSV)</summary>
       <p class="settings-section__lede">
-        Drop a portfolio CSV from any broker &mdash; Trading 212 is recognised
-        natively and other formats (IBKR, Fidelity, Schwab&hellip;) are
-        auto-detected. We&rsquo;ll parse it and show a preview before importing
-        anywhere.
+        Drop a portfolio CSV from any broker. We&rsquo;ll parse it and show
+        a preview before importing anywhere.
         <br><span class="muted">T212 export path:
         <span class="neu">Investing &rarr; Your Pie &rarr; &middot;&middot;&middot; &rarr; Export</span>.</span>
       </p>