Activate January banner for PNSQC event

[Copilot]

Conference/Workshop Details

N/A - This PR modifies the promotional banner, not conference listings.

Checklist

• Build runs successfully

Changes

Activates the January promotional banner for PNSQC's "Jam with PNSQC" event.

Banner content (_includes/banner.html):

• Updated text to "Come Jam with PNSQC! Learn more."
• Added link to https://mms.pnsqc.org/Calendar/moreinfo.php?org_id=PNSQ&eventid=190750&utm_source=testingconferences
• Applied rel="noopener" and aria-label for security and accessibility
• Removed unused empty <link> element

Banner animation (_sass/_layout.scss):

• Added display: none to #promo to enable jQuery slideDown() animation
• Removed stray semicolon

Banner slides down on page load via existing promo.js implementation.

Additional context

None

Original prompt

---

This section details on the original issue you should resolve

<issue_title>January Banner for PNSQC</issue_title>
<issue_description>1. Activate the banner
2. For January make the banner say "Come Jam with PNSQC! Learn more."
3. Turn Learn more into a link "https://mms.pnsqc.org/Calendar/moreinfo.php?org_id=PNSQ&eventid=190750?utm_source=testingconferences"</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes January Banner for PNSQC #841

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