Prepare v0.3.1 changelog and announcement

apps/marketing/src/content/changelog/v0.3.1.md

@@ -0,0 +1,39 @@
+---
+version: 0.3.1
+date: 2026-07-31
+title: Remote edits and easier discovery
+summary: This release surfaces remote edits in chat headers and improves OSS discovery, download conversion, and public marketing assets.
+githubRelease: https://github.com/Threadlines/threadlines/releases/tag/v0.3.1
+highlights:
+  - title: Show remote edits in chat headers
+    description: Chat headers now indicate when a conversation has remote updates so collaborators’ changes are visible from the chat list without opening the thread.
+    evidence:
+      - f6985290
+  - title: Improve OSS discovery and download conversion
+    description: Marketing and download pages updated to make open-source discovery clearer and improve the download conversion path from the public site.
+    evidence:
+      - a9a10f69
+  - title: Add and standardize social/brand assets
+    description: New four-panel X banner and formatted social banner markup provide consistent marketing assets for public pages and social sharing.
+    evidence:
+      - 85b3d5bd
+      - a9a10f69
+alsoImproved:
+  - description: Download page content adjusted to increase clarity for visitors
+    evidence:
+      - a9a10f69
+  - description: Social banner markup formatted for consistent rendering on marketing pages
+    evidence:
+      - a9a10f69
+  - description: New four-panel workspace X banner image added to brand assets
+    evidence:
+      - 85b3d5bd
+social: |-
+  Threadlines v0.3.1 is out 🧵
+
+  • Chat header shows remote edits
+  • Improved OSS discovery & downloads
+  • New four-panel X banner
+
+  Release notes: https://github.com/Threadlines/threadlines/releases/tag/v0.3.1
+---