feat: add /gsd:join-discord command

Lets users quickly access the GSD Discord community invite link
directly from Claude Code.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

commands/gsd/help.md

@@ -352,6 +352,14 @@ Update GSD to latest version with changelog preview.
 
 Usage: `/gsd:update`
 
+**`/gsd:join-discord`**
+Join the GSD Discord community.
+
+- Get help, share what you're building, stay updated
+- Connect with other GSD users
+
+Usage: `/gsd:join-discord`
+
 ## Files & Structure
 
 ```

commands/gsd/join-discord.md

@@ -0,0 +1,18 @@
+---
+name: gsd:join-discord
+description: Join the GSD Discord community
+---
+
+<objective>
+Display the Discord invite link for the GSD community server.
+</objective>
+
+<output>
+# Join the GSD Discord
+
+Connect with other GSD users, get help, share what you're building, and stay updated.
+
+**Invite link:** https://discord.gg/5JJgD5svVS
+
+Click the link or paste it into your browser to join.
+</output>