Promote InnerSource Hackathon pattern to Level 2 (Structured)

Move pattern from 1-initial to 2-structured for publication in the
InnerSource Patterns book. Enhance the Solution section with structured
guidance on preparation, participation, and event format. Add Related
Patterns section, add to the InnerSource Program Mind Map, and update
patlet, context, and status.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: rrrutledge

pattern-categorization/innersource-program-mind-map.md

@@ -8,6 +8,10 @@
 
 ##### [Start as an Experiment](https://patterns.innersourcecommons.org/p/start-as-experiment)
 
+#### Engineers lack time and safe space to try InnerSource
+
+##### [InnerSource Hackathon](https://patterns.innersourcecommons.org/p/innersource-hackathon)
+
 #### Slow community growth hinders InnerSource
 
 ##### [Dedicated Community Leader](https://patterns.innersourcecommons.org/p/dedicated-community-leader)