feat(pecan): add pecan release notes (#144)

* feat: add pecan release notes

* ci: 🚀 creates preview environment for pr144 [skip ci]

* chore: 🚀  released stjudecloud.azurecr.io/stjudecloud/docs:pr144-5f25dc0-263
 to pr144 [skip ci]

* revise: spelling

* chore: 🚀  released stjudecloud.azurecr.io/stjudecloud/docs:pr144-d574fb2-264
 to pr144 [skip ci]

* Add PeCan press release design document

* Add PeCan press release draft

* revise: format updates

* ci: 🔥 removes preview environment for pr144

* revise: remove plans and fix link, file name

* feat: add release notes intro, video, and expanded descriptions

---------

Co-authored-by: stjudecloud-cloudy <stjudecloud-cloudy@users.noreply.github.com>
Co-authored-by: stjudecloud-cloudy <devops@stjude.cloud>
Co-authored-by: Clay McLeod <clay.l.mcleod@gmail.com>

Author: 4 people

content/4.pecan/5.release-notes

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+---
+title: PeCan Release Notes
+navigation:
+  title: PeCan Release Notes
+description: A running changelog for the PeCan project.
+---
+
+Hi there! Welcome to the PeCan Release Notes page. Here, you'll find a running log of new features, improvements, and changes we've made to PeCan—along with a bit of the rationale behind why we're making them. Check back after each release to see what's new! If you have any questions, feel free to reach out to us at [support@stjude.cloud](mailto:support@stjude.cloud).
+
+## February 2026
+
+This release brings a major set of user interface changes to PeCan, including redesigned navigation, integrated help guides, and updated keyboard controls. Watch the video below or read on for a full breakdown of what's changing and why.
+
+<video controls width="100%">
+  <source src="/img/pecan/release-notes/feb-2026-announcement.mp4" type="video/mp4">
+</video>
+
+### New Features
+
+- **Redesigned Navigation.** New left-side navigation panel for easy navigation between data facets and access to the [Diagnosis Search](../../2.cc4k/1.index.md). This redesign lays the groundwork for a new cohort building feature that we expect to land later this year—stay tuned!
+- **Help Guides.** Navigation to our PeCan Help Guide documentation is now accessible on the new left-side navigation panel. We intend to continue contributing heavily to PeCan's help guides in the months and years to come.
+- **Keyboard Controls.** Updated [keyboard controls](../../4.pecan/4.accessibility/keyboard-shortcuts.md) to quickly access PeCan's Diagnosis Search. Our goal is to continue sharpening the experience of using PeCan seamlessly for frequent visitors.
+
+### Improvements
+
+- Accompanying all of the user interface changes, we've updated the position of the Diagnosis Search on the PeCan Homepage to better fit in with the new position of the navbar.
+
+We welcome feedback on these changes! Anyone is welcome to reach out to us at [support@stjude.cloud](mailto:support@stjude.cloud) or via the chat bubble integrated on the site.

content/4.pecan/5.release-notes/1.index.md

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+title: Release Notes